[ Ref. Mark Washek in 180326 MMDigest ]

I'm wondering if the wooden pump arm bushings might be in need of
replacing?  There are two bushings in each arm.  Often, when they
are worn, they can knock.  Re-bushing them is not too difficult,
providing any traces of grease are removed and a high quality bushing
cloth is used.

To remove any trace of grease from the old pump arms they should be
soaked in lacquer thinner for about a week and then cleaned of old
glue.  New bushing cloth can be glued in place with hot hide glue.
Be certain to avoid getting glue on the movable part of the bushing.

Bruce Clark