I have a 78 450SL that lost a plastic timing chain guide which sucked into the cam sprocket which threw the cam out of time which ate all the exhaust valves in that head. I am in the middle of doing a valvejob and the manual says to check the hydraulic compensator for the valve, push down on them with a hammer handle and replace any that collapse faster than others. Well a couple will compress very easy (and return) but MOST of them I cannot move at all. They will rotate okay. Can I pull them out, soak in some cleaner (what cleaner)? Please don't tell me to replace all of them $$$$$$. Thanks

Hard to test the capabilities of the hydraulic element. The ones that are easy have probably drained the oil from them. We always collapse the lifters in a vise to remove the oil otherwise the lifters extend and the valves don't close for a while.

I would replace any you suspect and put it together. If its noisey its easy enough to fix later. BTW if you are cutting the seats and valves (the ones not bent) you should verify the compression of the hydraulic element in the installed extended position. Another reason to get the lifters free of oil; so that they easily collapse to their proper extention/compression. They usually pop out alright but often don't collapse after being extended (only under the load of the valve springs)