the starter sleeve is starting to crack on my 27
The original sleeve was rolled into place with a very narrow wheel. If you look towards the inner edge of the sleeve (opposite of the slotted end), you will see this narrow groove. Use a cut-off wheel or a hack saw to remove the old sleeve. The new sleeve has two slots milled in it on opposite sides. You slide the new sleeve into position and then you take a narrow punch and tap the narrow strip of metal down into the groove that is in the starter drive. The narrow strip of metal is the strip between the two milled slots.