I read the prior post regarding the freshwater tank overflowing and not stopping.  We purchased a 1990 Beaver Contessa 37' this spring and I have not been able to get the FW system to pressurize.  First, the tank fill valve was sticking (probably from non-use) but that got working again.  Then, when I would turn on the fill switch and attempt to fill with pressurized potable water from hose, the tank would fill, than overflow and keep overflowing.  I have read there is an overflow valve circuit or other switch somewhere that possible is not detecting the tank is full?  I can't find anything on the RV like that.  Any suggestions?  I am new to this so it could be operator error as well.  I need a dang manual....didn't come with one.
Thank in advance for any help.
Brian
1990 Beaver Contessa 37'