Husqvarna 50 Workshop Manual page 29

Using oil pump drive gear puller P/N 5025026-01 and
sleeve P/N 5025099-01, remove the gear from the
crankshaft.
Separate and clean the oil pump components. Exchange
worn or damaged parts.
Assembly
Thread the oil pump drive gear into the sleeve P/N 502
5099-01 until the end of the gear is flush with the end of
the sleeve.
Assemble the puller P/N 5025026-01 to the sleeve
without the center bolt. Using a brass or plastic faced
mallet, drive the gear onto the crankshaft.