Hello, Cathy. If you're having trouble removing the shoe in position for removal then it may be jammed in the track. This can be real difficult to fix, especially if the sash is still installed. My first recommendation is to lubricate it with oil and see if that helps get it to move again. Hopefully it's just a little hung up and will slide with just a little convincing.
If that doesn't end up working then I think you should consider having a local professional come out and take a look at it for you. I'm less concerned about breaking the pivot bars, which can be replaced, than I am about accidentally cracking the vinyl. That is not the kind of damage you want so I think it's best to play it safe.
As for replacement parts, I can at least help you with that. What you have here is an older version of our 15-192 pivot shoe, which is used with the Series 170 coil spring, 15-156 cover, and 15-157 bushing. Note that the cover and bushing can likely be replaced as long as they're in good condition. The same goes for the shoe, too, assuming you can get it out.
One important detail to note is that some past customers have told me that the modern 15-192 is not the best replacement for the old shoe. The reason they gave was the bumps you see on the face of our 15-192; those apparently prevent it from installing comfortably in the track. In all cases, shaving or sanding those bumps down fixed the problem.
Note that any product altered in that way cannot be returned for a refund. Just something to keep in mind if you find yourself in that situation. Hopefully all you need is the spring so you don't have to worry about any of that.
