How to adjust a Franz LM-4 Electric Metronome?

I have a Franz LM-4 electric Metronome. I don't think the company repairs them anymore. Yes, there was something wrong, since my wife couldn't adjust the beats per second. I opened it up and found that the center screw needed to be tightened to the adjustment shaft - BUT at what position of the shaft?

While I had it open, the copper strip with an ~90 degree bend in it got loose and fell out. Don't know what it does or where it should be inside.

There are 2 metal screws that are probably supposed to be used for speed adjustment, but there must be some procedure to follow & I don't know what it is. Any help out there? Any former Franz technicians able to help?

Thanks, George