Flying these past few days has been interesting. I use a Logitech Extreme 3D Pro joystick. I guess I have a bit of mileage on the thing and lately my trim switch has been acting up. The trim switch certainly gets the lion's share of work compared to the other switches on the stick (except, maybe, the Hat switch).
I use the two top left buttons for elevator trim - it's a natural as my thumb is directly over these two switches and makes it real easy to access the trim. Now, though, the nose up trim (aft button) works fine but the nose down trim (fwd button) stutters. That's the best descript