I've just noticed that unlike seemingly every other pin I have, my Zacc Space Mission does not have a symmetric playfield support (i.e., when the bottom side of the playfield needs to be accessed). On my 70s Bally SSs, there is a nice little groove that the playfield can rest on where it leans at a low angle on the backbox. Now granted, there is a long set of 3 x 2 studs (I am presuming they are the size in metric) supports on the Space Mission upon which to support, but no groove - and it is not an easy glide to get it to those 3 x 2 studs as one side has a notch to go on top of, and the other side has a gap to over. I've had to lift it up with a single arm, and even though I am old weight lifter, it's still tough!
I have a hard time believing this is stock. It's like the configuration on either side would work (almost) if the other side were symmetric.