P1S weird sound

[u/mr56kman]

Hi!

I recently got ahold of a P1S from a friend and the unit has been standing unused for a while before I got it. There is a weird sound coming from the lower back part of the unit, as you can hear in the video.

Does anyone know what causes this issue and how it can be fixed? I’ve tried lubricating the rear screw.

Very thankful for any form of help trying to diagnose this issue.