1988 '90Q knocking aux. pump

["studentper" <studentper@email.msn.com>]

the auxiliary vacuum pump on the driver's side of my 2.3L engine is making a
horrible knocking that sounds like valves, but my mechanic says it isn't.  I
know this thread surfaces every couple months or so, but after searching the
archives couldn't find instructions for a do it yourself solution.  anybody
have a temporary fix?--the mechanic wants around $450 for a new one or $150
to "clean" the old which might quiet it for about 6 mos. or so.