[morzh]

There are two schools of cutting the cap:

1) cut close to the bottom, so that the cut line is somewhere withing the clamp holder. Then a plastic tube (plumbing pipe of the right gauge) is glued inside and the two halves are aligned and glued.
Advantages: easily restuffed as the access to the bottom where the new caps are located is unrestricted.
Disadvantages: 1) The plastic tube take space and gives less space to the new caps, 2) Good only for the clamp mount.

2) Cut the cap off. Then upon cleaning, restuff and re-glue the cap back on.
Advantages: looks good without clamp (good for both clamp and nut mounts).
Disadvantages: tall cylinder makes it more difficult to work on the bottom.