I’m having problems with lack of brakes in a 580sle and am starting with the simple things before I go to the axle removal. I removed and stripped down the master cylinders hoping it was them but they look perfect. However when I was reassembling them I noticed the flow valve and seat (3 & 4 in pic) are in mine the opposite orientation to what the manual shows. I believe these have not been touched from factory due to family history. I’m wondering if this could be some of the problem although it used to brake fine.
Ifn the brakes functioned OK with the master cylinders the way they were, don't alter them now. The brakes are most likely worn out.
That was my thought exactly mate. Gulp, here comes another learning curve…. And a hefty price I’m led to believe!