i have a tub master aqua flow jetted tub. the pump shaft drives. the impeller turns. but there is no air/water getting through the lines. there are a few bubbles that come up when i first turn it on but then...nothing. i have installed new o-rings on the tubing connections to the pump and it appears that the tubing/lines going from the tub to the pump have a leak elsewhere. the tub is sandwiched in between the shower and the vanity and is almost impossible to access the backside of the tubing, which is up against the exterior wall of the bathroom. how do i test for leaks without being able to access the tubing? is this an impossibility? should i run a line through the tubing to see if something is blocking it? please help.