Bent Sprocket

One of the segments came off of my Komatsu D155A-1 dozer, and it bent the hub inward on one side. It looks to be about 1/2 inch out of round. The segment on that bent section now rubs against something (not sure what the part is called yet) about a foot in diameter. I probably won't be able to justify the cost of buying a new sprocket from Komatsu, and it is difficult to find used parts for this machine. I have a few questions (1) Can the sprocket be made functional by shimming the segment which is on the bent side, so that it doesn't rub. I realize that the shim would have to be the entire length of the segment, possibly welded to the hub, and the bolt holes re-reamed to be aligned without play. It would probably only have to be 1/4 inch thick. (2) Do I needs special tools to remove the hub. (3) Are there any other dozers whose sprockets would match mine. If I could pick up a used sprocket, I would prefer to do that rather than try to fix a bent one. (4) Are there any other dozers whose sprocket segments would match mine. It looks like Komatsu has all 6 segments as one part number. I only need to replace 2 of them unless it is a bad idea not to replace them all.