Mark & Debbie Mueller
I had a similar problem, the piece disintegrated. For an interim fix I used a SharkBite fitting available at any hardware store. I would not use this as a permanent replacement due to the conditions these boats are subject to over time - I believe the SharkBite would fail. I ordered a replacement fitting from FaucetsComplete.com item Zurn QACA33MG Pex Qicktite Brass Male Adapter. This fit directly into the brass valve body and connected to the factory PEX tubing even though it was millimeter tubing and the fitting was for imperial size tubing. Check your valve body size to be sure the two thread sizes match.
Brass Ring A54