I'm guessing it is just 43 yr old glue. So I'm going to try to pull it off once the heat picks up around here. Might make it a little more flexible and try to pry that puppy off. Thanks for the insight though. I wanted to put a new knob on or a custom knob of some sort. A outfit here in Southern Cali called mooneyes has some cool knobs to try. Not too pricey either.