Freezer coils icing up, fridge too warm

Had to remove inside panels to expose coils in freezer. Used hair dryer and towels to de-ice. Reading online learned about defrost heater (long thin glass tube with wire coil in it I could not see b/c up under the inside of the coils). Who would have guessed freezers have heaters in them!! And learned the defrost timer (inside the fridge) is just a continuous clock turning on and off the defrost heater. Anyways I used a screwdriver to turn the timer to defrost mode and by disconnecting the wires from each end of the heater and measuring the voltage, I found 70 volts there. Hmmm. I didn't know what was the right volt amount.
Reading online I also found out the defrost Thermostat is basically a temp actuated on/off switch for that heater, so that while the timer is sending *120* volts to the heater (which gets red hot by the way) the therm switches the heater off when the temp gets high in the freezer.
I eyeballed the therm ( it looks like a little can) and I saw that it was coming apart. The key at this moment is you can cut out and bypass the therm to see if the heater works. If it does you know the therm is the bad boy. But only do this as a momentary test or the heater will probably set your fridge on fire after a while!

Always remember to unplug the fridge when you are messing with the wires! And dry it up inside before putting your hands and tools in there!

So I ordered a therm using the model # of the fridge. Had to cut the old out and strip / wire nut the new one in.

Took too long b/c I was hung up on the heater being bad (after all it didn't heat up when I put the timer in defrost) and not knowing about the rights volts to the heater.

PartSelect helped out great! Thanks!