dripping shower head

[Mary]

My 1974 double wide has a stall shower in which the shower head is slowly dripping. The on-off-temperature handle has been replaced and has one of those Allen wrench hole things to tighten.... I know how to do this, but I don't think that it's loose or that it would cause the shower head to drip.
Am I wrong? Any ideas what is the problem on this maddening shower head? We have stopped using the shower (there's another one that works fine) but suddenly the shower head will begin dripping again, even after not being used and just sitting there quietly for days.
I have thought of finding the shut-off valve, which I'm sure is under the sink, and just shutting it off, but that probably is not a good solution because I'm sure it would turn off the sink water too!
Help!

[Mark]

Sounds like the shower valve.. being that old, you probably cannot get new gaskets for it and should just replace the whole thing. Moen makes decent stuff and it's not too expensive.