I have a Sequence 3600 pump that has worked great for ten years, but lately it stops pumping tho it is still running. The water in the basket falls below basket intake and it loses suction. Obviously if algae clogs basket or gasket or lid are not secure there will be suction issues. But this is happening with clear water and it not happens after just few minutes of refilling basket with water and turning electricity to pump back on. The flow is certainly less than when pump was new but I am wondering if that is the way a pump can die, just slowly losing the suction to keep drawing water thru 10 feet of buried pvc and filling pump basket. Is it just time for a new pump? Any recommendation for similar size? Pond is 1200 gallons with nice waterfall from 3 feet height, moderate goldfish ( and one catfish) load.