I've rebuilt a number of these pumps here in the UK -- including failed
rebuild attempts -- and have corresponded with several MMD subscribers
about them.  See my previous posting at

  http://www.mmdigest.com/Archives/Digests/200804/2008.04.14.09.html 

I've not found it necessary to alter any valves.  It is important to
ensure the anti-slap crossbars allow them to open sufficiently to
minimize pressure in the exhausters.

Staples through the rubbercloth to secure the card stiffeners seemed
a poor idea to me.  The problem with hot glue is it sets brittle and
repeated flexure of the stiffeners however slight eventually makes it
fail.  The right adhesive in fact renders staples unnecessary.  I used
good quality homogenous card bonded to the rubbercloth with high
quality PVA.  No failures have occurred in 20 plus years.

The largeness of the stiffeners depends on the rubbercloth.  The thicker
and stiffer it is, the larger the radii of the creases, and the smaller
the stiffeners must be to allow for these.  If they're too large they
will start to peel off.  A moment's thought will show that though
stiffeners could be attached to the outside of the exhausters, inside
is more secure.

Paddy Handscombe
Wivenhoe, Essex, UK