oil pressure gauge repair?

Has anyone repaired a leaky oil pressure gauge. I have a '79 240D and the gauge is leaking, and I'm wondering if these things have a gasket or something inside that could be replaced and stop the leaking. I don't want to start messing with this thing if it can't be repaired, or if it is going to be a Major headache. I'm also considering disconnecting the gauge in the interim(while I'm fixing it/waiting for the new cluster), and am wondering the best way to do this. Cap the end of the line, or pull the line and thread a plug off where line comes from. They don't seem to be pipe threads, and so I imagine it's probably going to be difficult to find proper caps/plugs. Thanks to anyone willing to read and respond, -Bones