Was working on the Bolens 850 this afternoon getting close to starting it. Checked for spark and none. Started to check with the meter and found power back to the coil. The wire from the coil to the points was shorted. Wire alone was OK. Removed the copper tie bar, points were open and all OK on that part. Checked the stud and it was shorted. Removed the stud and found no centering collar on the bottom insulator. Nothing to keep the stud fro shorting out. Found nothing in my parts drawer that would work. Checked the "O" ring box and found one that would fit in the cast hole and snug around the stud. Put 3 over the stud and put it back together. Now have spark. With a little luck I should get it out of the shop, put the front blade on and it is ready for a new home. May not be OEM but bet it will last just as long.