Judge dredd flipper

[Waterfairy]

Hi all, new on here so be nice please.
I have swapped my flipper optos because I had a lazy lower left flipper. Since this the lower on is fine but upper left is not working at all.
Any suggestions for a beginner to look at doing?

Many thanks

 

[Jagspete]

Check the fuses, uppers are often on a separate fuse, also check wiring is right way round on work you did and nothing dislodged

 

[drhex]

And make sure both optos on the left button are opened on pressing it. You can also swap boards around between left and right.