Looking for diagram for 66' 250SE self leveling rear suspension
 

Hey all, going through an old 66' 250SE and needing some direction on the SLS. I have some experience with the W123 set up but the W111 is arguably a funkier setup than the former.

Its leaking badly and its sagging when it sits, but does operate properly over the road, so maybe the leveling valve is bad, leaks down when the car is parked?

Anyhoo, I think I should see a reservoir and some mechanical bits on or around the axle, but I need some help, a diagram would be very helpful and any thoughts would be appreciated as well.

TIA Doug