Oh...what I wanted to mention, before I got sidetracked....regarding Mike's suggestion about adding humidity w/o popping the lid...I wedged the end of a plastic drinking straw onto the end of my smallest funnel, taped the joint in place with electric tape, cut of the excess straw length, & stuck it into one of the plug holes, right above whatever I use to hold water...should work like a charm.
Just to clarify, adding water without opening the lid is for lockdown.
If you need to add water before then to keep RH where you want it, does it not make sense to do it w/o opening the lid & letting even more humidity out?
The RH is all about air cell size, having it take time to go back up matters less than how long it takes for the temp to get back up. Cooling time is now a feature in more expensive incubators, it's reasoning is hens get up each day to eat, drink and take care of other business. This cooling period is supposed to improve hatch rates. Personally I don't worry about opening to add water until "lockdown".