What usually happens with the HRO dials is that the setscrew scores the shaft, and the burr keeps the knob from coming off. I have always managed to get them off, but sometimes with great difficulty. I just recall pulling forward on the knob and finally working it loose. Sometimes it will rotate on the shaft, but not come forward. Avoid rotating the knob on the loose shaft; that will score a ring around the shaft and make it even more difficult to come off.
I have never had to actually destroy a dial to get it off the shaft. I just tapped on the front of the knob, then pulled on it, and eventually got them to slide off.
Early models had only one setscrew. Later models had two, located 90 degrees from each other.
Don k4kyv
