I’m not sure it needs to be rebuilt, but I just got this 1980 Puch Magnum MKII the other day and want to restore her. The piston wasn’t moving and after some PB Blaster it’s slowly moving. The person I bought it off of said it was sitting a couple years but had previously run until the carb and other parts were stolen. He said he never changed the pucks or did any work on it. I ordered a set of pucks and plan on hopefully this week to pull the head off of it and taking a look at the top end.