Small Engines (Lawn Mowers, etc.): Snowthrower doesnt work

Question
I have a Honda Tractor HT 3813 with a snowthrower attachment. Everything was working great until a large tree branch entered the auger from the side. The auger tried to snap the branch and I heard a slight whine and then a snap. I noticed that a shear bolt had snapped where the shaft from the gear box meets the innner auger... sorry I'm not fluent with each part. I replaced the shear bolt, checked the pto belt and started the tractor back up. when I engaged the lever for the pto the pto spun under the tractor and started to spin the yoke to the snowthrower.. but the tractor would stall right after I threw the pto lever. This scenario keeps happening. The tractor will keep running as long as the pto is disengaged. I took off the housing covering the sprocket and chain and all looks good. I have a feeling its the gear box on the front auger. I tried to turn the auger by hand, and it will not turn. I engaged the pto when the tractor was off and the auger would not turn.Let me know if I'm on the right track. if its the gear box is there a manual specific to the snowthrower? Its a H-0242(model#). Any help would be greatly appreciated. If theres no manual could you give me some advise on how to remove the gear box on the auger.

Answer
I could not find much on the H-0242 model number.

I did find the following snow blower manual for the HT 3813

http://cdn.powerequipment.honda.com/pe/pdf/manuals/SB1013A-AH.pdf

I would start by disconnecting the belt at the snowthrower and see if you can turn the pulley by hand.  If you can not rotate the pulley by hand then I would remove the chain guard on the side of the blower and then re-try spinning the pulley.  If you can turn the pulley then you know something is the auger is causing the problem.  If you still can not rotate the pulley then you know something between the snowthrower pulley and chain drive is the causing the problem.

Eric