[C320-list] Floor Shower Pump

[Craig Zicari]

I turned the shower pump on and while the pump motor ran it was not 
pumping the water.  Then a heard loud sound which turned out to be the 
small insert plug blowing out of the top of the vent hose elbow which is 
in the cabinet on the wall behind the head.  I put the plug back in; the 
pump did pump the water but it blew out again. 

Do I have to replace the elbow to get one where the plug will stay in.  
Any idea why it blew out.  I am assuming that there was an airlock in 
the hose.  Or could it be that the drain was below the waterline so it 
would not drain.  We were at the dock and water was quiet; the boat was 
not rolling.

Thanks.