I will go bounce the rear of my 560SEL at lunch and let you know how mine reacts.
As far as looking for leaks, mine had one where the leveling pump discharge line curves around the passenger side front of the engine. The line had rubbed against the block and worn almost through. Try looking around up there. It will show as a drip on the floor right under the smog pump.
Also check your oil level. I have read on this forum where the seals in the pump leak oil into the engine when they fail. So, if your oil level is rising for unexplained reasons....
I will revise this post after I bounce my car. Good luck, I hope this helps.
1989 560SEL (172k)
1989 325IC (122K)
2004 Suzuki Volusia LE (3500 miles)
2005 Yamaha Road Star (20 K miles)