Where are those little "lost" pieces going? Maybe right through the pump and into the bearings? I'd suggest fabricating a new strainer screen of some type. I've had pretty good luck using pierced sheet metal that's available on Ebay with small round holes, maybe 1/16" diameter or so, and forming/silver soldering it into a strainer.
Jerry


"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!