I have a Epiphone Japan Les Paul (Japan Market) and I want to replace the pickups and pots and caps with some higher quality components. This guitar has the older-style amber top hat shaped knobs and the ring with the pointer underneath. Are these knobs supposed to pop-off somehow? These particular ones are really "on-there" and if anyone has any tips on removing them then please let me know. Also what determines if the guitar needs long or short shaft pots? Thanks.