I'd be confident that you have a foreign object lodged in the pump. It has a fairly robust impeller and you don't need any tooks to check it.
If you disconnect the power and open the inspection panel at the front you can see the water drain pump. See photos at these links. http://users.wcnet.net/dadoes/F&P-Repair/24_pump-in-place.jpg and http://users.wcnet.net/dadoes/F&P-Repair/27_pump-mount-bracket.jpg
You don't need any tools but you will need to lift the release clip and rotate the pump body anti-clockwise around 1/4 turn.
The pump should drop down. (You may need to disconnect the wire/plug). You can leave the green Earth lead attached if you just want to inspect it. As the pump is rotated, a cup of remaining water will drain past the pump so have a rag or sponge handy! Then if you can't see the remains of a plastic toy or button or other object already, poke your finger up into the hole and check there. Be careful with your finger as the foreign object may easily be a glass fragment! Once you have checked that area, also check that the pump spins freely and replace it in the hole. Rotate it clockwise until the retaining clip re-engages. Re-connect the wire and presto!. I hope this helps.
Frank
September 2005