Printing press- lights aren't turning on. Tested them initially and they worked, and everything else seems to be fine. I don't really know how I'd troubleshoot or fix this?

Would have probably been good to have a mention of checking it works whenever you place the thing intended to press the mechanism, because now I wouldn't know how to take it apart to fix it. I think I'd have to unscrew it and everything, which of course I don't want to do.

The actual printing works fine, just not the lights.