More info then:
Step one, determine if this is a design problem that was always there, or a component failure problem from some condition that changed.
-Did something change, or did it do this as long as you have owned it?
-Did it ever work properly?
-when? First start of season, first start of day, while hot, while cold, was it running ok for hours, then blew.
-How? When extending, when returning, when under load, no load?
-Any evidence of air in tyhe oil? Compressedair in the cylinder, when the valves shifts to retract, can blast a huge flow through the return line many times larger than pump flow. The compressed air acts like an accumulator.
Ultimately It is likely caused by a high flow exceeding the flow of the element at that bypass pressure, fully opening and bottoming the bypass valve, and still not handling all tyhe flow the the pressure drop rises to make the flow go through.
I have seen many times filters installed backwards, so backwards flow through the element inside to outside, so element collapses and bypass valve doesn't function because the head is backwards, and head splits.
