Ah, the typical shutter capping and uneven spacing of the P6.
This is very often the case with this otherwise wonderful camera, the design of it hails back to the Praktisix (I own one) and there were some things not manufactured or designed properly.
The film spacing problem can come back when adjusted and the whole mechanics were never revised during the whole time it was produced. The shutter capping is just a problem of old grease.
Not having proper lubricants is a problem with which almost all of the East German manufacturers had to deal with, it dries up and then smells like candle wax (Carl Zeiss Jena Alu lenses) or it vanishes and ends up as a residue on the aperture blades (the MC CZJ lenses).
Having a properly working P6 or Praktisix is a joy, I mean how good is the Flektogon 4/50 alone?
All the best for yours!