If the inserts have sunk, but are level, you can remove them by taking a socket that is about the same size as the inert and tap it with a hammer until it comes out. You will do this from the bottom of the playfield and the inset will come out of the top. You can then glue them back in level. They are not difficult to remove.
That some wax and a clean ball may help on that playfield. High tap the transformer and set it up on 3" adjusters on the as suggested by currieddog.