So, of course, my rack is having more problems. I currently have the Iris Sweater Box rack with the heat tape underneath, and I have the VE-100 thermostat

I've had both for about 2 or 3 years now, and about a year ago my thermostat started having problems. It would just randomly shut off, so now it only stays on if it's in a VERY specific position. If it accidentally gets bumped out of position it turns off.

Anyways, my NEW problem is that my temp gun is showing me that some of my shelves are several degrees below what is set on the thermostat, and what the thermostat says the temps are at. I have the thermostat set to 92 degrees (this makes the bottom of the tubs about 89-91 degrees) and I have the probe tucked between the heat tape and the second tub (second tub from the top). Only my top tub and my bottom tub are at the temperature that I have the thermostat set to. The second tub (the one with the probe under it!) is reading 85-88 degrees (even though my thermostat is saying its at 90-92 degrees!), and the third tub is reading 82-85 degrees.

I don't know what to do! I can't just turn the thermostat up, because the top and bottom tub are at the temperature that I set on the thermostat. And I can't really replace the heat tape because all the heat tape is connected. It's all just one big piece of heat tape that goes underneath each tub. Not to mention that I would have no idea how to replace it all.

I'm not sure if it's the heat tape that's the problem or if it's the thermostat.
Has anyone else had this problem or know what to do??