Went to a local camera repair shop, he wanted to bill me 100 Euro (~ 112 Dollar) for just the one seal between revolving back and camera body. So I now ordered a light seal kit and will replace it myself. I'll try to follow Shutterfingers (thanks Shutterfinger for pointing it out in the image) suggestion as well and see how the next film turns out.
@Kevin no bent foam visible, but I'll replace the RB seal
@480sparky it is an SD back, as far as I know they changed it from S to SD model
I'll post the result as soon as I have them, thanks @all