I have the C21 operation manual and along with the information I have found here I am making head way. I have some push pull pots with short and long sleeves but they are 500k for guitars (mostly Fender) but I don't have any in the 1k range that is where I had the problem. I have 2 1k pots with switches coming that have short sleeves but I can make an adapter to screw on them and also be a spacer that will work as the original pots did. I had checked cts first thinking that was possibly what was in the rig but could not find a match but the ones I have on order will work but won't be the oem like I wanted, to keep it original. Thanks for the information you can never have too much information.