Mine went on my 1100S, they were done under warranty. I also changed them on my GS. Basically I think the bearings (it's usually the ones at the rear end of the S/A, where the bevel box mounts) are simply undersized for the huge torsion forces going through them. It's not a tricky DIY job, hardest part is getting the preload on the bearing correct, taper rollers, so I just do them till any play just goes away, rather than trying to use the official torque figures.