Welcome to The Forum!
I think we may have some confusion about whether it's the lid on the filter or the pump that is leaking. Also, pressure dropping doesn't usually cause a leak as long as the gauge is on the filter lid
Any chance of a pic or 2 of the equipment pad and the filter and it's gauge?
Luv & Luk, Ted
Having done construction and service for 4 pool companies in 4 states starting in 1988, what I know about pools could fill a couple of books - what I don't know could fill libraries
Thanks for the input. I have found the problem. The lid o-ring gasket was cut in two.
Ah-ha! Mystery solved!