Need help replacing the defrost heater and thermostat. I pulled the tray out of the top of my GE Monogram that has the evaporator and compressor.

The housing around the evaporator is tack-welded to the aluminum tray. How do I get the evaporator out to replace the defrost heater element? It seems impossible without drilling out the tack welds on the aluminum evaporator coil housing but want expert advice before I do this.

Also, there appears to be 2 thermostats...do I replace both or one of them?

Part #'s
WR9X502 & WR50X108.

I already replaced the Defrost Control and that didn't fix it. I hope it's the defrost heater and or thermostat.

Thanks for your help.