We (dealership I am service manager for) have replaced a lot of solenoids over the years for various reasons. Have you removed the valve? Have you tried to find another source for the O ring? We had one a little while back that had a hair line crack in the manifold and we replaced the whole pump and motor assmy under warranty. Good luck and keep us posted.
Mike, RVIA & RVSA Certified Master RV Technician
Amy, Dr. Assistant - Roxie & Mei Ling, four legs each
2000 Gulf Stream Scenic Cruiser 450 hp & 1330# torque
06 Saturn Vue, 06 Chevy Z71 4x4 & 2014 Corvette Z51 M7