Just to add to the previous posts, it is not unusual to have plastic bits inside the fresh water tank (especially on new coaches....not sure what year yours is?) and it can take a few years sometimes to get all the bits out of the fresh tank. If your water pump filter is clean (no bits) it is possible that it is leaking air around the seal, which will prevent normal pump flow (air leaks in the low pressure side as mentioned by a previous poster). You mentioned that you have winterized the coach before, so try shutting off the fresh water tank valve and use the Winter suction line to test the pump. Just use a sanitized pail (or jug) of fresh water, and pump that into the system. If that works well then your filter and pump are good and the problem is upstream from the fresh water tank valve.
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