I've check the eos and seemed ok, looked similar to the LHS one. Couldn't find any loose wires as well. The leaf switch that is physically activated by the flipper button seems to be very close to the ball release trigger mech. I can't see for sure but would love to test this theory by raising the playfield and trying the flipper. But no fuses yet. I just wonder if when activated it is also touching metal or something on the ball release mech.

Is this a possibility or highly unlikely?

I'm more of an economical flipper player and don't over do the flippering or need to hold and trap balls, so that's why I reckon the problem didn't become that apparent after the rebuild.