Hi! This is my first mail on this site, so be gentle!

I have a problem with one of the servos on my glider: it works fine, then suddenly pitches up or down and stays there while juddering away about that new point. I can still apply up and down inputs, but the trimmed position is a good way up or down and the whole elevator vibrates.[&o] I've tried swapping receiver channels and it continues with that servo only so it's not a transmitter or receiver problem.

Makes flying a bit tricky!

Any ideas what is going on here?