RC Boat Problems-Help plse!

[randomness5555]

Hi guys. As I know some of you forum goers are pretty good with electrics I was wondering if you'd know what was going on with an RC boat I'm having problems with. The boat is pretty old (my dad built it when he was young but we know it did once work) and has a hand built speed control, which we again do know worked originally. What is happening is that the throttle on the remote is not causing anything to happen-but we know it isn't the remote or the receiver because we tested them with a spare servo. However, the steering causes both the rudder to move (as normal) but also the motor to spin some distance before stopping, and turning back again when the steering stick is released. In other words, the motor is trying to work like a servo.

Anybody got any idea what's wrong with it, or is it most likely just a failed component?

[LordFerret]

I would think the receiver (in the boat) is old and tired and suffering from some sort of signal splash-over into the channel which controls the motor. What manner of radio system is it? You say it's old ... PCM/FM?

[randomness5555]

AM apparently. I guess that might be it. We've tried the other servo in the port for the motor, and that worked like expected. Thanks anyway, it looks like I'm going to have to replace the radio components-it is pretty old after all, might as well replace all of them.