My plan was to scan the surrounding area if/when i ever got around to a rebuild of this game, and recreate a little overlay for the area.
That could work on this game as that area of the playfield is similar all over that section so it would be quite easy to 'select' a similar spot and scan it, re colour it etc and do a little overlay. The hardest thing would be making the 'edges' of the overlay as invisble as possible as there are very few 'straight edges' to 'work to' in that spot.
What I would NOT do is try and just 'fill' that worn oval shape itself and blend in to those already blurry edges, MAYBE there is a way where you could find 'edges' in that pattern very close to the worn spot and cut the wear into a larger , squarer shape ( yes make it a little worse that it is ) and then create a square -ish decal
Alternatively you could fill and smooth that section and instead of a decal , match some paint and re-paint it in your best efforts to match that pattern, it is SO repetitive and there is so much 'fleck/speck' in that pattern that if you did a decent job it shouldnt stand out too much
If anyone has a decent section of this PF and they scan it and send it to me I am happy to tidy it up so that anyone that needs it can have the little art file as a decal.