My 1st big project was Alien Poker.
I sent all the boards out for flat rate repair.
Had a new flipper switches installed. The right was a pain.
Thingaverse had a file for the drop target spacers. I found the targets came out warped as they cooled unevenly.
Otherwise, should be all about the playfield inserts and wear on the initial launch path.
LED's were easy BUT you have to get all the bulbs out. I had a few stuck and it looked crazy until I got them all swapped out.
Usually the displays gas out. Buy a new kit.