Thanks for sharing this solution. I've been dealing with this exact problem on a used universal tool rest that I recently purchased. It only took a few minutes today to implement your fix. I had been considering more drastic measures, such as complete replacement, or a maybe welding or brazing, but was unsure which option to try. It was fun to play follow the leader instead.
I did replace my apparently undersized roll pin with a piece of 1/4" steel rod and pressed it in from both sides to expand it to a tight fit, then punched it a little more for extra measure. Also, when drilling the set screw hold I intentionally drilled a slight divot in the vertical shaft to help the set screw hold it all in place. It's very solid now.
BTW - The part number for the replacement tool support and shaft assembly for the universal tool rest is 521794. It is currently priced at $48.05 plus shipping and handling.
Last edited by dstensland on Sun Oct 04, 2015 5:57 pm, edited 1 time in total.