Should always be two wires - cant see how any pump would run with only one. Are you sure its the pump youve replaced? Trace back the waste pipe it should lead directly to pump.
After that Check the filter unit for blockages.
Disconnect pump from sump hose and check for obstruction in either item.
Locate the pressure switch - a round item about 3 inches across. Its an air operated switch which tells the machine water has reached the correct level. Disconnect the rubber pipe from the switch and blow down through it to clear any blockage. Switch itself may be faulty.
WASHING MACHINE SERVICE AND REPAIR MANUAL.
cut and paste the following address into your browser for more info. www.2ndwave.co.uk/manual.html
dan
February 2008