[C320-list] Pump Guard ????? - How to inspect, check etc

[Brad Kuether]

I am having problems winterizing my shower and fridge drain.  I am getting no suction what so ever.  I took the hose off the thru hull and tried again, nothing.  So I have narrowed it down to either the pump or the PUMP GUARD.  

Does anyone know how the "pump guard" works?   Is it a filter?  I couldn't find any info on it in my owners packet.

Does is screw off to reveal filter or some other type of magical device?  

Thanks so much.  We are coming out next week.  I can do this part on land but would rather just "get it done" now.

-Brad, Mary, Monica, and Jarod
"Independence"
2004 Catalina 320 Hull 1006
Middle River, MD