Hello, I have a PoolCo MultiPort valve on the sand filter tank and I need the sight glass. The one that is there now is plastic and has started to turn yellow and signs of getting ready to crack. Its not leaking yet, but im afraid when it goes I won't have anything to replace it. Is there a replacement for this. I don't see the part number listed in the manual. I see you have sight glasses' but I don't see one for the PoolCo mutiport valve. Can you help me with this please?