I recently reconditioned the Harrison heater in my 54 3100. 10 amp fuse should be okay. There should be a fuse holder on the back of the switch. That should already be part of the circuit and all you need to do is plug in your new 10 amp fuse. You can hook the power supply to the ignition switch. That is how mine is wired and I have not had any issues. Not sure about your switch problem with the ceramic tube. Maybe a small drop of silicone from a hot glue gun? These do get hot from what others have posted and it could get hot enough to re-melt the glue. I am assuming your truck is still the original 6v system and has not been converted to 12v. If you are 12v the original fan motor will not last long before it burns up. The original switch will work with 12v. You can order a replacement 12v motor from AutoZone. Below is a link to the replacement motor. They cost about $30.

Link to AutoZone Electric blower motor

Last edited by dgrinnan; 01/20/2017 3:03 PM.
Dave from Northern Kentucky
My 54 3100