Quoted from djblouw:
So, I have a new irrational hate. Cleaning clear coat out of rollover inserts is terrible. They REALLY need to come up with a way to mask these before spraying clear.
Bally had star insert that "plugged" the star base.
After the game is clear coated, the assembler would tap out the
plug from the bottom of the playfield. the sad part about this process at the time was
that it tore the clearcoat from the top of the plastic star base insert.