Could be a failing TP1 (in transformer) or TB2 (on output rectifier).

 

Anyway to bypassing the thermal switches Duane and let the fan run constant?

 

Sure. Locate wire #1 at fuse F1 holder and run from there directly to fan motor wire #20. This will by-pass both TP1 and TP2 causing the fan to run continuously when the machine is powered up.

If it still cuts in and out with TP1 and TP2 by-passed then I'd check the fuse/fuse holder and fan motor for issues.

 

Mine used to do that until I replaced the klicker disk t stat. The stock one was pretty pricey, so I found an HVAC disk with the right temp range and used that, cost a few bucks.