I was referring to the check valves in the pump,
if you are unfamiliar with them you would probably
be money ahead paying a Local Dealer to check
out your machine for you.
Here is a link to a pdf file showing a break down
of a model TS2021 General Pump.
http://www.generalpump.com/PDFs/TS2021-Pump.pdf
You might try a search on this BBS for Troubleshooting