Rollbar won't stay down

Any one know what is wrong with the rollbar on my 94 SL500? After I put it down, it slowly comes back up. The dealer doesn't seem to know........ but is willing to charge me "time and material" to learn, (can't afford blank checks).
Help
Don

sounds like a hydraulic leak due to a bad ram or valve

I noticed a small leak at one of the roof locks at the windshield (about 2 to 3 drops all winter). Is it part of the same system? I really don't mind paying to have it fixed it's just that the MB dealer scares me with their hourly rate and can't give me an estimate.
Thanks,
Don:uhoh: