GE Model 11 Gas Detector Relay

More information would be nice.What type of gas,what pressures are you dealing with,type of oil,how is this relay used in the circuit?A diagram of it's current use would help us to help you.

My opinion, based on limited information at this point in time is a leaking diaphragm that isolates the oil from the relay.You may be able to disassemble and repair the diaphragm using red RTV silicone to seal the edges.I would only do this as an emergency repair, due to the liability consequences of subsequent failure.("Hot Potato" theory).

If this is indeed, as I suspect, used to monitor transformer gas, a new unit is cheap insurance against a major transformer fault.

Do not be penny wise and pound foolish.

http://www05.abb.com/global/scot/scot252.nsf/veritydisplay/ffb560e6db7ce747832574d0005861de/$file/1zua5492-505_gas%20detector%20relay%20model%2011%20and%2012%20.pdf

So this IS for transformer pressure monitoring.Refer to the AB manual section 3.2, 3rd paragraph where it describes the isolation between the oil and actuator mechanism.

You probably have a cracked metal diaphragm,which is not economically feasible to repair,nor would it be wise to do so.

My advice is replace the unit with an AB unit.They may not be physically identical, but should function in a like manner.(IMHO)