Finally bit the bullet and removed all the playfield inserts today (15 of) .. unfortunately about 15% of the side of one broke, but it should be Ok to go back in.
Have decided to cheat and leave them out while I do the playfield touchups.
Next jobs on this game are playfield touchups and cabinet repaint.
Will post some progress pics of that when I do it.
Have already got all the new parts I need for this game and am itching to put it all back together so i can play it for the 1st ever time,  but keep telling myself to finish the cosmetic work first 

You are doing a great job. Don’t be afraid to do touchups. If you use artists acrylic u can easily wash off what u don’t like. Aim for 0, 00, 000 taklon brushes. I would also remove the old lacquer on the wood around the flippers and bumpers. If you use an old fashioned shaving blade it comes off easily. Here is a result: