Quoted from megalo17:... I'm hesitant to try and level them on a newer game. ...
I haven't done it on a newer game, but on WPC era and older. Why is newer a problem?
I'd say you have nothing to lose. I would do a test on one. Heat it up from under side with hair dryer or hot air gun. If you haven't done it before, be conservative at first. Find the right heat level when you can start to move it. Push it level with playfield. I would do this with the playfield vertical from the sides so you can have one hand on each side. When level, epoxy around the bottom of the insert. If the lip really is recessed too far it may make a good ledge for epoxy to set on.