Possible "Quick and dirty fix" - Press on the adjustment rings in various spots and try firing again.
I have an earlier chrome version of the lens, and when I first got my hands on it I had the problem of the cocking lever sticking and not fully returning when fired. (Also had a fully jammed aperture blade assembly.) I ended up gutting the lens and cleaning a shocking volume of gunk out of it before it was usable. However I have noted that pressing on the lower part of the shutter speed ring can cause it to still jam up.
If everything is moving and tripping as you would expect, then it most likely is a decent lens that is just in need of cleaning and lube. There is a very slim risk that you could have a weakened spring, which would make things a little harder to service at this point.
How fond of fiddly parts are you? They aren't terribly difficult to work on at home with some basic tools. Small set of jewelers screwdrivers goes a long way with these lenses. Take lots of reference photos, work on a white cloth, and be VERY careful about springs if you do take the plunge. Otherwise sending off to a professional is probably a wise investment.