Kitchen gray water tank is draining very slowly. Ideas?

[living the dream]

So my kitchen gray water tank is draining very slowly, not much coming out at all. Is the only cause a bad valve? If so, anyone know what size I need? I have an Alliance Avenue 36BRM 5th wheel.
Is this what I need?

Valterra Bladex Waste Valve for RV Gray Water Tank w/ Drilled Stem - 1-1/2" Diameter​

 

[Jim Beletti]

It could be a bad valve. It could also be the steel wire inside the sheath of the cable pull has come loose at the valve. That’s repairable.