I have a problem with flow to my spa jets that seems like an obstruction. Normal water flow to my pool and spa returns is fine, but when in spa mode (suction side valve turned to spa return and pressure side return valve turned to the spa jets) my filter pressure goes way up and I'm getting very reduced flow from all the spa jets. I opened the pressure side return valve up and it is fine. Fed my shop vac down about 2 feet into the line and sucked out a few gallons of water, but that's it. I'm worried that something from my heater came loose and went down the pipe. Any help greatly appreciated.