I am looking into replacing my volume and tone control knobs on my BBN4. The factory knobs, to the best of my knowledge, are glued on. I don't see a set screw. I am looking for the best and easiest way to pull these knobs off without damaging my bass. Should I just pry or do I heat up the knobs? I have the replacement knobs which have a set screw. So the installing of the new ones shouldn't be an issue.