I have this problem since blowup the first 74LS541N, the controller of port 1 and replaced with socket + new 74LS541N.
No way to move up, the remain actions, fire, left, right, down are working. The Port 2 is Ok, all directions, fire, etc.
Tested with 4 coleco original joyticks, all with this issue, no up movement.
What pin control the up movement? May be a faulty track? Which? Any help?