I was being sooo careful disassembling my 54 3100 but alas it happened... a 1/2 inch bolt wrung off. Dadburn it! After thinking about it over a couple of beers, I remembered that I had a couple of 1/4" left handed drill bits. After center-punching the stub I put one to work. I drilled in about 3/4" thinking it wasn't going to work when all of a sudden rrreenckk and out it came! "Weee Doggies!" As Uncle Jed would say!