Good find, Greg. It looks to be in good shape with only the slight modification to the US penny. One of the major problems with that modification (other than the obvious molestation) is that the small US penny will most likely not be heavy enough to consistently trip the ball release lever. As you noted, removing the plastic shims inside the coin slide will return the mechanism to original.
I like the current backflash with the UV softening in the main play field. I would not mess with that were it mine. As Mr. PM noted, the coin entry plate should not be a significant challenge to recreate.
Well done on acquisition.
Contiguous State Collector