Well if all you loose is the airsoft function consider yourself lucky. I fried my Tamiya MFU trying to get the Heng long recoil to fire from it. I lost the up function on the BBl elevation. Luckily I have a Heng Long cam in it so now it functions like A heng Long. I have to cycle the cam to get the bbl to go up and down, but it is still basically functional. I quit experimenting before I cooked something else that would make the case terminal.

So you are not alone at having the odd failure or two!!!!!!

I ripped out the airsoft guns on my two Shermans so I have nothing to go by. Hopefully someone can post a picture of the stock wiring. I took pictures, but I failed to get a shot of the turret wiring, so I am coming up empty..