To do it right needs the mirror box removed.
I don't bother.
Remove the cover plate surrounding the lens mount...4 screws.
Remove the Top left screw in the lens mount. Camera FACING you.
Benji recommends going through the bottom, the result is the same but going in through the front puts you just above the offending pivot point.
Hold the camera at about a 45 degree angle, wind side down and with a pinpoint oiler/syringe or other pointy thing apply a small drop of oil. Let the camera sit for a few minutes and work the shutter a few times. If it isn't completely healed, do it again. SMALL drop.
Watch oil would be best clipper oil is also very fine. NO WD-40, no 3 in 1. Watch oil is clear and has a viscosity like water.
I can't stress how important the oil is. Check with a watchmaker and see if he can give you a few drops in a film cannister