Hey,

since the marks from magnet play are deeper than the planking ,
i think 3 or 4 coats of clear will solve the problem
sand between coats to level, you don't want a big layer of clear in the end, just enough to protect.
The playfield is'nt that big either so it won't cost much to do the clearcoating.
Meaby eltimbo can make an offer for the clearcoat process.
In Belgium i would do it for 40€ all in. I dont know how expensive clearcoat is Down under?

What other factors to consider? I dont know?
It won't be that easy to find a good (better) replacement.

grtz
free