Originally Posted By: Bill Cody
I suspect one of the rubber cups is broken/cracked and causing the binding or locking up. I think a rebuild should be investigated. There are instructions here and on line of how to rebuild those pumps. Sprkplug a member here does rebuilding of those pumps. Here is some additional information. Sprkplug and I have rebuild kits available for those GAST pumps. The rebuild procedure for Gast and Thomas rocking piston compressors are similar.
https://www.youtube.com/watch?v=JvVv2iRDVz8
http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=390615


FWIW I bought a pump rebuild kit for my 75R from Bill C. when I was buying an inlet filter upgrade kit he designed. Figured a reasonably priced pump rebuild kit would be nice to have on hand should the need arise. I suspect Sparkie can hook you up with some reasonably priced items to have on hand as well.

Last edited by Bill D.; 07/02/15 09:47 PM.
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