Really surprised such a common complaint was left unanswered. You probably
already know the score - but just to help make the record here complete...
Answer: The symptom you describe is the number one glitch with the FS-GT3C.
There are several mods suggested on www.rctech.com for relocating the power
switch. This one mod is considered mandatory on this model by many.
Another solution is replace it with a FS-GT3b or go all the way and move
up to the incredible FS-iT4.