I sure would like to find out what the original amount was with this machine. Does the model number have some sort of decoding?
No....they don't have manufacture build labels, like on automobiles.
Whatever decoder guide that's sandwiched in between the coin-in optics and the size of the slot hole on top of the button deck pretty much tells us what denomination the cabinet was originally set up for.
Take the coin-in optics apart and show me a photo of both sides of it.
There WILL be a part No. molded on the plastics.
You need to take the coin-in optics apart anyways...there could be dust balls starting to block up the three optic holes.... those should be cleared of any debris so the optical emitter beams can go thru to be picked up by the receiver optics.
If you have the coin hopper for the machine, place a quarter on the top of the wheel shelf and snap a photo of the coin sitting in between the wheel nibs.
I could tell you what hopper wheel you have.