window regulator question

What is wrong with the one you have?

It won't roll down, seems like it is stuck solid. The previous owner (a bodyman) said it needed to be replaced but he could never find one. I haven't taken off the panel to check it out myself, maybe I should before buying. I 'm laid up for a while and didn't want this one to get away if this stuff is hard to come by as I 'm thinking.
Bob