Tom,
Good idea on the brass bushing. I have basically checking every one I drill. I had been thinking if the cap in the drill guide starts to hog out I would make one in steel, but a brass bushing sounds easy.
I was getting crazy drilling holes and had to do something different for a while! If all the side rails turn out okay I will try to make them in steel to add a bit of weight. I'm thinking I may also add some lead ballast where I can as well.
Jim