Is it locked w/ a collar? Model# of thrower?

If, after a close inspection, it is determined that
there is nothing locking it in position, then it may
be a 'press fit', in which case a press or a bearing
puller will need to be used, depending on which direction
it must go. A thorough cleaning of the shaft, along with
the liberal use of penetrant is always helpful. If all
else fails, then it's time to break out the ol' hot wrench.
Not necessarily cutting it, but often a little heat
applied in the proper location will expand things enough
to allow them to break loose, (being careful of any seals or other things that the heat would damage). Don't worry
about paint,(that's what they make buzz bombs for).

Thanks for the replies.
It is a model # 486.24839.
There was a colar that heald the bearing into the back of the impeller housing but I removed it. The shaft wont pull out the back of the housing far enough so I can get a puller on the bearing. I guess I'm going to have pound out the roll pins that hold the impeller in place. They are sort of hard to pound out, and I imagine even harder to replace. Thanks,

This recommendation may sound taboo but it works, cut the old bearing off the shaft with a reciprocating saw and a fine tooth bi-metal blade. It may leave very small, shallow cuts in the shaft where you cut the innner race free of the shaft but these are of no consequence if you don't cut any further than you absolutely need to.

An adaptation to this method is to use a thin cut off wheel in a grinder. Cutting the old bearing is far more common than most people will ever realize as it doesn`t introduce large amounts of heat into adjacent components that aren't going to be replaced.