Since you said it was bent, that would indicate that the person who assembled the machine used the wrong bolt. I have a correct bolt sitting next to my computer keyboard that has a head marking of M113 that I picked up at the Kubota dealer last month for my blower. I have no idea what that head marking means and Googling it didn't come up with anything. According to the parts book, it is supposed to be a grade 5 by 1 1/4" x 1/4" bolt, but I am unfamiliar with the head marking. I believe that once you get the gearbox off everything will come apart with almost no effort. Most likely it is only the fan blade that is bent. I see no need for a puller, to take any of the parts off the machine. If you need a puller, you have a bent shaft, which is extremely unlikely. The rock stopped the rotational force of the fan, not the shaft. I believe that the fan has moved rearward or forward (most likely) and that there is a misalignment that you are trying to work against. Don't keep beating on it with a hammer. You need to unbolt the auger shaft from both sides and remove the augers from the front. I would do this first to relieve the pressure. Make sure to mark the augers right and left because they are different should they come off of the gearbox shaft.
In the end, you might have to take the rear gearbox off and work toward the front. I only had one gear-driven snowblower apart and that was a while ago. It was the same thing, the neighbor ingested a potato-sized rock and had the identical problem that you are facing. Once the fan was loose from the front gearbox, it spun freely till it hit a high side of the housing. We heated and straightened the fan and it was fine. Kubota orange paint will hide many scars and mistakes. Just be patient and you will be fine.
While you have the fan off, drill the center and put a grease fitting in there to keep any rust from forming. Fill it up once and forget it. The other thing is that you can skip the grease fitting and paint the shaft with never seize. It is a personal preference.
On a used blower that I purchased, I found that someone put the lock washer under the shear bolt head, and that caused a misalignment of the cut grooves in the shear bolt. I had a hard time driving it out, but once out all I had to do was run the proper size drill bit through the hole to correct the alignment, and it was never a problem.
