My guess is that you can see the piston and a ring or two between the block
and the sleeve.

If son get an adjustable hose clamp that is big enough to go around the
piston - if to small, use two and string them together.

Put some oil on the clamp,piston and ring, and then tighten up the clamp and
use it like a (narrow) ring compressor.

If its still balky, you may need to put the clamp so it only covers half the
face of the ring -toward the block- and slide the sleeve onto the exposed
face, then remove the clamp.

PITA. Good luck.
Thomas Forhan