by cleaning my underdash-wiring from the previous owners "additions" I repaired the brake light switch plug and looked by chance to the brake booster rod to pedal linkage. Once, one of the previous "mechanics" had reversed the bolt which connects the pedal with the rod. Therefore the nut was only very loose some threads on and the bushing in the rod was destroyed. Luckily I discovered that
It doesn't bear contemplating what could be happen some hundred miles further 
Thank good I looked at the linkage... Now I need a new bushing for the brake booster rod - what type I need and where can I get one?
On the bolt there was only the nut - is there originally a washer or something like that underneath because it is a moving linkage?
Thank you very much!
