When a engine is running, it generate / produces a kinda low frequency wave that will affect electronics. This is true, always keep the servos cables tidy & sometimes if you notice when we held the glow heater towards the engine, the servos will glitch a little when fireing up.
Novak is famous for ep stuff. Could be this Rx too sensitive to such vibration cause by the engine.
Try borrow an Airtronics Rx from a friend using the same crystal as before. It may help.