To seal, the O ring must have pressure from expansion where it seals. To do this in must compress as it enters its resting place. The grooves in the sleeves must be large enough to have room as the O ring compress between the sleeve and block it has to expand somewhere or it will shear off the extra and then would then not have the material to expand to form the seal. Then they would leak.
Remember when installing even the old used sleeve it must be able to turn 360 degrees all the way down in the hole without the O ring. If it does not you are in danger of shearing the new O ring which will then leak.