Well, I finally found a couple of 'round tuits' this weekend and got the job done. Before tackling this repair I would suggest you either 1) Buy a plasma-cutter or 2) buy a stack of grinder cutting disks, a dremmel, and a SERIOUS amount of stubborn-ness! (Since I'm cheap, I went for the latter of the two.) I'm documenting this repair for anyone who needs to do this.
To start off with, here is the impeller. For those who don't know, the hub in the center of this pic is the culprit. As you can see, the top (front) half has a hole for a roll pin and has a smooth-bore. The bottom (rear) of the hub is splined to accept the male shaft of the gearbox. That splined section is what goes bad and needs to be replaced.
Below you can the "vanes" of the impeller are cut away from the hub. This took about 4 cutting wheels on a dremmel. I tried to use the dremmel to cut through the base welds, but it just wasn't enough to get through.
As you can see, a standard angle grinder won't fit in to cut these welds.
The best way to get at this is to go at it from the back. Look at the grinder-dust all over the garage floor. Not fun!
Here is the old hub removed from the impeller, compared to the new replacement hub.
Both the old hub and the new hub is cut in half and welded together. In the end, we're going to keep the right side with the spirol-pin hole and smooth bore, and replace the left (splined) side.
Three nuts are used to provide the hub the proper height alignment with the impeller-fan prior to welding it back in.
Then time for some paint to cover up those ugly welds!
Finally, reassemble the blower and test your work.
