Hi conquest 96, as grumpy has said, it's good at the OutdoorKing Repair Forum if you can us give the make, model numbers; complete engine numbers and some pics of the offending part and of the overall machine...this gives us the opportunity to give you the correct advice that is specific to your machine.
If I was to hazard a guess, I would say you were talking about a Scott Bonnar Model 45 engine shaft....the key, if it seizes in its slot; (usually because of egress of water or moisture) can be a stubborn devil to remove, in my humble opinion, I would try:
Using a liberal amount of penetrating oil over a period of 1 to 2 days and then tap gently on
one end and being half-moon shaped, hopefully will slide up and out of its groove
Please let us know how you get on....
