Alex, it's quite possible that the blade wobble, isn't a problem with the blade holder. These saws have special bolts that they pivot on, plus a flat connector rod at the rear of the saw. These parts are all on the interior of the saw, and they all wear out with normal use. I think that if you check the pivot points out, you'll find that that is where the wobbles come from. I've owned two of these saws over the years, they worked great. But, after so much use, these pivot point bushings and bolts needed to be changed. If you try using a heavy grease on these points, it should help solve some of the wobble problems, The only thing though, is that doing this is just a quick short lasting fix. The only thing that will give you satisfaction, is to install all new bolts and bushings. I'm not to sure if the parts needed to solve these issues, are still available. The last time I ordered them, I couldn't get all that I wanted. I'm sorry to say, but,I think you were sold a boat anchor.
Len