Thanks Peter for the concern. Yep, safety has always been on my mind when messing with circuits. ( History )=== I started in the electrical trade in 1969. Got into Ham radio in the early 70's and have operated and built more than I can remember numerous transmitters, receivers, and lots of accessories for them. Most worked but had a few things that didn't work. In the electrical end, I have been a employee, contractor, and an estimator over this time period.
Now to the safety of this project. When I found it at the thrift store I thought it was a new one. It still had the plastic cap over the plug as shipped. It looked like it had never been used. When I plugged it in there, the motor made a terrible sound and the heat didn't work. I got it real cheap and had a good idea and hoped I could fix it. When I got it home, I took it apart and found the fan blades was hitting the frame, so I shimmed the motor and that cured that problem. Checked the heater and found the inline series fuse was bad. It is a one time fuse about the size of a small resistor. No markings on it for the temp. limit. I found the thermostat wires were wrapped around the thermostat and looked like it could have caused the therm. to not operate right. The heater winding's looked new and not burnt into. So, I bypassed the fuse and the heater works. I then replace the power cord with the unit I made years ago for another one that quit working because of the motor bearings finally wore out. If it had been used, then the fan intake could have been blocked since the intake is on the bottom and could have restricted the air flow.
I hooked up the external dimmer from the last one and adjusted the voltage for 102 degrees and that keeps it at a comfortable temp. After unwrapping the wires from around the internal thermostat, I played with the internal thermostat all day to make sure it was working OK. So I have it set up to use the dimmer control to set the temp. and the internal therm. to use as a higher limit. I keep a metal thermometer in the top lid and can check on it often. I'm never that far away from the unit and I also have a fire extinguisher close by also.
The one I had before finally gave up the ship because of motor bearings worn out. I've been using this one for the last few days and have let it operate about all day to dry some enamel paint on some parts on a kit I am working on.
I appreciate the concern on this and I think it will be OK. If not, the fire station is just a few blocks from me. LOL