First....I'd check for a crappy solder joint on your packs.....If you're running stick packs, I'd tear them apart and re-build them as side-by-side packs. Then check your motors for wear. Next....it could be your crystals...you'd be suprised at how fragile they really are!! Also try popping open your reciever, blowing any dirt and crud out of it and checking your antenna wire for frays.