Sounds like a Crown 1. But What Peg don't know, nobody knows.
IF it is a crown 1. Sometimes the in-water pump seal goes, and the drain hole is blocked and water
gets to the brushes
, then they stick and the motor
goes really slow.
Sometimes the key on the macerator head
rusts, and the motor spins but the pump wont pump. There are too many questions, you need to be a bit more specific, a photo
Look for the model number under the two brass brush covers at the back, you might have to wirebrush the paint