YES, please retain parts for this game. You can no longer get many parts on the playfield PCBs. Break a switch and you're screwed.
I obtained one of these a few months back and ended up having to replace the "3" target. Unfortunately, because NOS or repro drop-in replacements don't exist, I had to wire in a normal standup target from another game. That led to the board not mounting properly, and multiple top lane rollovers not registering because of flex in the board. Even if I raised the board and adjusted the rollover switch arms, the pop bumpers would have no way of registering. That led to having to rip out all the old switches on the bottom board, install brand new normal parts (including new lamp sockets, because remember that those are on the board itself too), re-wire everything to the points on the PCB and extend the mounting of the board to the playfield. It was a lot of work and I'm happy with the results (especially having proper pop bumper leaf switches), but it's not something anyone should want to have to do because one switch died.
On a side note, I highly recommend "modernizing" this game a bit. Stock out of the box it's not that great, but lower the flippers a bit so they hit the ball harder, put a power ball or globall (the later is preffered) in it, LED it out, wire in a couple extra bulbs in the back to brighten things up, and replace those flipper parts too (chances are they are 40 years old and need it anyway). When this thing flips and plays fast, it's a lot of fun.