The thing is that there are only a few JP kits that are available, one of which you have purchased. I'm not sure that there are spare parts available, but I can understand you wanting to buy one so that you can quickly replace it for the one you have now. It's easy for a few of us to just say slap some bondo on the thing and fix it, when it may not be as easy as it all seems, but building the kit requires some work, and getting the parts as accurate you want needs a little work. If you're concerned about the time issue and would like the security of having a complete part in a short amount of time, I would only suggest that you at least attempt to improve the one you have now, only because if you can't find a replacement, you at least have something to use. It may not be as accurate as you would like it to be, but it would be better then having nothing and trying to fix it at the last minute 