Correct me if I'm wrong here, but I'm pretty sure we had these pumps in Australia a good six months before anywhere else. The first (or second) pump I bought had this exact same problem all the way back then. I have always fitted bearings the same way and never had a single problem. This one pump ate 3 sets of bearings, and in the end, I sent it back to my local supplier who was good enough to offer a replacement. The new one was put together the same way and has been perfect since (around 2 years)
Unfortunately it seems a bit hit and miss, but my advice is to have your supplier fit the bearings and shaft so you know you are covered in case something goes wrong. In saying that, I have one in my ski now that has been put together the same way and has been perfect. Also, I now use 6205 C3 Nachi bearings as suggested by my supplier. So far so good.