Welcome to the Popperette club!! That has to be the best deal I have ever heard of for a Popperette. Take the small pan off (two thumb screws), that is located inside the machine. The pan either has a funnel or a flap and look to see if there is a heater there. I can't see how it can only get warm. It either works or it doesn't work.
If you do try to engage this heater electrically DO NOT UNLESS IT IS SUBMERGED IN OIL!!!!!! preferably in that small pan.
If the heater is good, not cracked, ohm the heater. If that's good, check the wires. Then ohm the switch.
If all is well. The low oil mercury switch, fuse, or mechanically the screw that makes the switch could be missing or not pressing down the micro switch enough.
Even a cracked heater can work as long as the wires are not touching each other.
Oh by the way, I'll give you $50.00 for it.
Let me know if you need any more help. P.M. me if you do.
GREAT FIND!!!