I have an attached spa on my pool with 4 jets. jets work great, yet one jet has barely any pressure. I usually run the spa without the filter in and if I take the filter basket out as well, the pressure is kind of there on the one jet with a problem, but still 20% of the strength of the other 3. If I try and block the other 3, the water just starts coming out the venturi valve. Anyone seen this or have any ideas? I'm guessing its something with the plumbing that I can't reach but maybe someone has some ideas.