I am still having rats squeeze into the chicken run through the door. I may try poison water over my winter break. It will involve more work (locking chickens in, plugging in poison water, and in the morning: dumping poison into a bucket and removing it along with poison waterer, setting out and plugging in regular water, releasing chickens), which is why I want to wait until I have time off. By then I may be able to do the job in daylight.
Meanwhile, I might have found a temporary solution. Just today, I crammed a 2x4 under the door from the outside (they appear to be going underneath and squeezing up through a crack). I'll have to remove the 2x4 if we are expecting rain or snow, so it won't freeze to the ground. The door opens out, so I have to move the 2x4 every morning just to get in the run to feed everyone, but it is worth a try.
Laying here is on a steady upward path. We bottomed out at 46 per week (I don't light, but I have 15 pullets). Early this month we had 61 per week, this week 75. I tried to sprout some red spring wheat this week, but the seed is too old. My chickens are locked up. I'm keeping an eye out for our raccoon visitor. Kind of hard to tell if he's been around again with no snow to track him.