1992 Kawasaki kx 250 Dirthbike Part trouble?

Hello I recently purchased this bike and I have the skematics downloaded to my computer and I have went to an actual kawasaki dealership so there is some other problem here. The problem is the gear on the water pump embly that attaches to the little fin and rides on the cog to the left if your looking at the engince cover from the right side is broke. I have ordered the part 3 seperate times from 3 seperate companies including a dealership itself. I keep getting the wrong part! I mean it is the right part but the teeth on the gear are too small and will not match the part that it is intended for. The dealer said that maybe it was superceeded by a better part and if thats the case I will have to buy the cog it mates with. I was just wondering if anyone else had this problem or could point me in the right direction. It has sat for 4 weeks and I really just wanna ride it! Thanks so much!