Gear is gonna get replaced? Get a Dremel or a 4'' grinder. grind a deep groove across the flats. deep, but don't go through. Use a cold chisel to split the collar to relieve hold on the pin.
Just completed installing new gear and axle. Only had to redo it once after putting it in backwards.
Everything works!!!
Hopefully it will last another 15 years. Do tecumseh engines last???