This is the similar set up on the little 100 series saws like 36/41, 136/141, 137. .... I cut/score them with a small Dremel cutting wheel at an angle, then smack the groove with a chisel. This cracks the gear apart without cutting into the shaft by accident. Must support the crankshaft with block of wood or similar when the hammer comes down! I place the crankshaft in deep freeze for 2 or 3 days. Get new gear and heat it up to 300 degrees. Oven works! They slide right on using welding gloves.
Before you remove the old one, check the depth of how far the gear is on the shaft. Put new one on the same depth.
Husqvarna 501866901 is part number for a new gear.
This is the puller for the little saws. I don't know if it will fit the bigger ones tho...
https://www.ebay.com/itm/1442443030...9wcU8cVQPQ%3D%3D|clp:2334524|tkp:BFBM7oXC_sJf