I am currently in the process of putting an overlay on a space invaders also. I should start clear coating this week. You should clean sanded playfield with naptha, clear coat sanded playfield, wet sand, level the lower areas like sunken inserts, clear coat a second coat wet sand if level then apply overlay I will be applying about 5 coats of clear coat then wait about 3 months to harden before repopulating. This is my first time but have done a lot of research

I would use these instruction but would wait longer to repopulate