The rollover button inserts on the playfield of a recently acquired January 1951 vintage Genco Tri-Score have shrunk and no longer fit snugly in the playfield cut-out holes.
The inserts are typical of old Genco EM machines of the late 40s and early 50s and are bright yellow with bright red 1-1/16" rollover buttons.
The rollover button inserts, after shrinking, now measure about 2-1/16" in diameter and the playfield cutout holes are 2-1/8" in diameter.
That leaves a generous 1/32" gap around several of the playfield's rollover buttons. Too much play for a snug fit.

Photos of the top and bottom portions of the playfield illustrating the rollover button insert fit issues are attached.
Button #5 is particularly troublesome.

What can be done to fix the rollover button inserts, or the playfield, so the rollover buttons fit and work properly in the playing field?

Thanks.

GTS_Bottom_Playfield_1 (resized).JPG

GTS_Top_Playfield1 (resized).JPG

I believe that I have found a solution to the restoration problem.

Most of the used parts available for this Genco Tri-Score restoration are also shrunken or warped and will need a similar treatment.
My approach to restoration is to apply Titebond "Quick&Thick" multi-surface glue to the outer perimeter edge of the insert being restored.
This glue dries clear and adheres well to the perimeter surface of the plastic insert.
It only takes one or two coats of glue to get the diameter of the insert ready for replacement.
If needed, selectively apply one or more glue coats to an insert that has an out-of-round perimeter.
When you are satisfied with the perimeter fit, you will need to sand and polish the play surface of the insert before reinstalling it into the playfield.

This technique has worked well for me.