This is on a Mystic. (Bally SS 1980). The ball hits the glass as often as not, off the center bank of drop targets.
The positioning of the drop targets on this machine does not seem to be adjustable. They are in a rigid box. A tech said there would be two adjustment screws accessible from the bottom of the unit, but the only screws I see hold the parts together with no room for adjustment. I don't see any adjustment screws.
Is it possible that a new set of plastic drop targets would fix the problem? Doesn't seem likely, I guess all drop targets are created equal, but that's all I can think of. No telling how old or new these are. They look fairly bright & clean. Incorrect design on them, though.
Something funny about them... the flat tops on each set of drop targets are not uniform. Each of the three banks of targets has one target where the flat top of the target is slimmer than its two brothers. I'm thinking that the former owner had different sets and mixed them up. Could that be it? (Same bullseye design on each.)