For $10, if it has a nice Yashica Yashinon lens, especially if it is a fast prime, you are still way ahead. There are hundreds of bodies that use the M42 lenses. Besides the ones that Ottrdaemmerung mentioned, older Ricoh, Sears, Chinon, Mamiya, Praktica, Petri, Fujica and many other brands. Look for ones with metal shutters, they stand the test of time better, and are easier to clean if they do get gummed up.

I would bet a bag of donuts that the root cause of your problem was tiny bits of gooey foam materiel getting into places where it didn't belong, like in the grooves of the shutter assmbly, and on the shutter curtain itself.