Idk but it looks like someone built a whole new box for yours. Is the shelf a red painted plywood? If so that's what all of mine was made of.
Sure it makes no difference and from what I see everything internal is the same and set up the same. Just got me thinking when you mentioned the thermometer placement.
Mine had the thermostats in that location with the screws sticking through the side. Also had the manual turner switch on that side and a red light indicating it was running. Mine had a meat probe kind of thermometer also on that side that went through a hole so the probe part was just barely above the self out at the front edge of it.
The problem with cabinet incubators is with size comes an issue of consistent temps throughout. It just usually doesn't happen. With my homemade one I use now I put the same type of meat probe thermometers at different levels to see how much difference the temps were.
Back in the day when I had one like yours what we were told to do is rotate the trays when staggered hatching. Start at the top or bottom then each week when you started a new batch you move the previous trays up or down a shelf.
That way by the time they get through a hatch cycle they've been on each level. That gives them equal time at each temp variation that's going on inside.
If you just set them the whole time on the same shelf then the ones at top would get a tad more heat and could hatch a day or so early while the ones at the bottom a tad less and hatch a tad after 21 days.
In theory it keeps your hatches consistent on when they hatch and gives them an opportunity to be in the different heat zones to average out overall instead of consistent a little high or a little low.
Of course you need it to be in an acceptable range at the top and bottom. Ive hatched for a long long time and accepted it as it is what it is for the longest time. Nature of the beast with a old style cabinet.
I've built some over the years and tried different things. My current one I had hoped to get it more consistent and in the end it was pretty close. My heat source is at the bottom and my temps were just a bit off at the very top. I ended up adding a light fixture in the top and a small wattage bulb. Have to give credit to my boy for the idea and it worked perfectly.
You can chase perfection but I've learned the bigger the incubator the harder the chase to achieve those perfect hatches like possible with the small tabletop incubators.
I feel your pain with the cleaning chore also. Been there done that. Seperate hatcher or hatchers is the way to go. I remember used to try using a shop vac with my cabinet. Pita. Now days every now and again I use a leaf vac and just blow the hell out of the inside of my cabinet. That works a lot better.
Gotta say- after thoroughly scrubbing the inside of it, I'm certain someone else had been hatching in for a while. The layers of green that rinsed off in my sink rinsing the rag had to of been baby chicken poop residue
I don't see Any other explanation for that color. My arms are probably short, being a woman, I would guess maybe it was designed by a longer armed man. If it were up to me I would of probably made it wider instead of deeper and made it to where the racks were either completely removable for cleaning or much eàsier to maneuver around. I cut my knuckles several times attempting to maneuver through the racks and into nooks.
As far as the box- funny thing is the original sticker is on it? But I had thought the exact same thing that maybe someone replaced the cabinet but in my research (haven't seen any photos yet) but I have seen people talk about a VERY old model that actually wasn't painted and was just plywood. I believe the next model that came out was the one that was painted red? Like what you're describing.
I have seen the models that had a hole drilled through for probe placement on the right side of the cabinet, along with the wafer adjustment screws. But there is no such hole on this one. There is a big Hole on the other side which I believe is for the water reservoir (it has a five gallon bucket that sits on top) that goes to a tub that sits on the top shelf with a float valve on it. That is where I have the probe for the digital thermometer pushed through now. Btw- should the reservoir have a lid on it? If so that's an easy enough fix.
If I drill holes into the side for each level just big enough to fit a probe through (like a meat thermometer) will that mess up the ventilation or air flow/temps at all?
The entire cabinet does seem to have some kind of clear finish on it (inside and out) I imagine to keep it together because of the high humidity environment if it wasn't sealed it would surely fall apart pretty quickly. It's plywood of course.
Here's another question - I know hardly anyone ever cleans out the back part (the compartment in the back where the fan and motors are) and if it was used as a hatcher I would think it's probably pretty bad back there which could cause the Incubator to fail eventually. Is there any way to easily access that part of it? So far it's looking like I would have to dissemble the top at the very least. Which, if I'm being honest makes me very nervous to do for fear I will mess up the integrity of the machine. But with this being as old as it is surely it needs to be cleaned back there, right?
Have you ever seen a candler like this? I think that's what it is supposed to be? It came with the Incubator. Looks homemade maybe? But I need to replace the bulb inside it. The plug on it looks just as old as the one on the Incubator so it made me wonder if maybe when GQF started they sent these with the Incubators?
The plug that is in the red extension cord goes to the Incubator. It says "Phillips Industries" on it. I don't think they are called that anymore? The other one is to the "Candler" and has a capital cursive L on it that has a little plug as the tail of the L.
You know- Looking at the cabinet now- the side that the thermometer hole should be on actually looks like maybe it was replaced. Like maybe it got damaged and instead of building an entire cabinet they just swapped wood for this one side? It looks different slightly and has a different finish on it kind of. All of the hardware on it looks right for GQF though
Actually now I'm wondering if Maybe they just resealed the edges? And the wood is all the original wood? That looks to be more plausible actually because the other side (turner switch side) has the same weird finish around the edges. But it also looks like something was taken off of the side that had been there for a while because the wood is two toned. What do you think might of been here? It appears to have once had something screwed in there?
I think maybe someone was preparing to paint it maybe and went around filling holes. There appears to be two places on the side of the wafers that look like holes that were filled? Does either place look right for the thermometer hole? Or did they used to have two one for a hygrometer and one for a thermometer maybe?
The hinges and latches appear to be original. There are some "star" screws (probably not the actual name) screwed into the back panel. Thinking those may not be original? There is also a screw on the door right under the label, maybe they had something hanging from it?
) Anyways. This cabinet is old and I suspect people have done some modifications to it over the years. I am not seeing a hole for a thermometer probe anywhere. Of course I can drill a hole myself but I want to make sure I put it in the right area. I only see a hole for the water tube. Does the thermometer go there? I can't imagine I'm supposed to take the temperature on top although that is what I'm reading? What temp should I start with up top, bc of course the bottom will run much cooler then that. If I put a second and or third probe where should I place those? Just drilled through the main side wall? Or can I place them on the door? 
