Joel,
Is it necessary that you must have an exact replacement or exact replacement
parts? I don't know a thing about your particular pump but it sure sounds
like the "innards" are worn out. The diaphragms make look ok but in reality
they might be warping out of shape when pressure is applied.
A new pump will save you lots of time and frustration and they are not
expensive. Why not replace the pump first and then spend countless hours on
the Internet looking for replacement parts for your antique pump? ;)
Tom
WBCCI 5303