None of the B7100's had a water pump, HST or gear. What you are looking at is the dynamo. I had to replace the bearings in mine last summer. There are two bearing to replace. You will need to bend a wrench to get the nuts off that hold all this on, or find some type of swivel wrench. When putting it back on, start that nut, the one that is hard to bet to, first. It will make it much easier.
I think the water pump was first on the B6000-7200 series.
I think the water pump was first on the B6000-7200 series.