Try cleaning out the port.
I had a similar problem, could not move forward on the joystick, cleaning out the port fixed it.
Spray some solvent into the port, and use a toothbrush.
If not, it is possible that there are some pins broken off (it's enough that just one pin is snapped) from the actual port, just where it connects onto the board, from when people have twisted the port around when inserting joy/mouse. I have successfully replaced a port on one of these boards once, all you do is buy a generic angled port for pcb mounting. They are readily available. Then, the easiest thing to do is just snap/cut off the old connectors pins, and then afterwards desolder them one by one, and then slab the new one in there. It's timeconsuming work but you'll get there easily enough in the end with a little patience.
By the way, greetings to Maine. I was in Maine on an exchange thing in 1994. Bass Harbour.
I remember there was a guy there named Jason who ran a BBS, which we'd log onto all the time to play tradewars. Don't remember the name of the bbs tho :crazy:
