When flushed the macerator appears to work OK. On clearing the pan there appears to be a blockage and there is a backflow of dirty water. There is also a slight water seepage around the top of the box when activated. The pump sounds noisy but powerful. There is no blockage in the 5 meters of horizontal 40mm waste pipe.
Sounds like the non return valve in the discharge elbow has gone or is leaking either replace it with the propper part or With the power of drain down the discharge and fit a vortoplast NRV in its place (01684 594590 for spares) or as a temporary repair fit a mcalpine T28 non return valve in the line
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