Stuck key on MVS 4slot

I recently fixed my memory problem on my Neo Geo 4slot and when the test screen came up I noticed that the "Up" counter on Player 1 kept moving. I rotated the stick a couple time but it kept on going. I haven't had a chance to diagnose it yet but I wanted to get some ideas of things to look for. I've read that some bad ICs can do this in the Big Blue Book.

Thoughts?

I had a similar problem on a Capcom cabinet. Start simple. Check the microswitch on the joystick. If it is broken or the spade connector is connected to the wrong prong it can cause this problem.