[Lee]

Personally i doubt it's a static build up from the track as this would cause interference all over the track rather than just 1 point, it may also cause it to shut down. I would also say it is a wiring issue, keep the receiver as far away from speedo/motor/ power wires as these will have a flux round them and potentially cause interference. Don't coil up receiver wires, leave it messy till you sort out what it is. Try the receiver mounted on its side also, wrap the receiver in tin foil, this helps sometimes.