Fresh water shut off valve on exterior of my 2010 i 2551 is drying out

In cleaning out fresh water tank the valve which is like rubberized and drying out and making it hard to turn.  Anyone else have this problem and can it be replaced, if so, is it an easy fix.? The top part is breaking apart and have to use plyers gingerly to turn it on and off without breaking off pieces.   

In cleaning out fresh water tank the valve which is like rubberized and drying out and making it hard to turn.  Anyone else have this problem and can it be replaced, if so, is it an easy fix.? The top part is breaking apart and have to use plyers gingerly to turn it on and off without breaking off pieces.   

Talked to Carol At PC and they are sending an new valve. Just so happens they have a few in stock.  So if anyone else has this problem the valve can be replaced.