After my last two failed in about 12,000 miles each (bearings, and I don't
over tighten the belt!), I broke down and went to the dealer.  Only factory
rebuit pumps were available (I need the 1.9 engine pump) for $135 exchange,
and I bought one.  I noticed that the factory installed bearings were of a
different design, and the clearance was tighter between the impeller and the
pump wall.  I'm going to press one of the old pumps apart and inspect it.  I
suspect inadequate bearing lubrication, since neither pump leaked, they just
got wobbly and noisy before I replaced them.  If the lube was as good as the
seals. . .

I felt bad exchanging an Italian made rip off core, but what can you do.
They didn't check it out, and I didn't want to pay another $75.

FWIW,

Stuart MacMillan
'84 Westy w/2.1