I just got a M88a which I believe is a shorter version of the M70a.
For starters, it was covered in a thick oil/grease for preservation. You need to clean everything including the magazines. One of the magazines had a large chunk of an insect or something inside.
One of the magazines seems to have a problem as the spring tension is way too high or there is friction between the follower and the magazine body. Finding replacement magazines is impossible.
I cleaned the gun off using mineral spirits and it is a rough finish. A bit of rust here and there, missing bluing, scratches (I used a soft tooth brush, so I doubt it was me). Probably will fire it next week, I hope it feeds hollow points.