Sorry to add to an old post but anyone searching on this might find it useful.
My 2001 HDi SX washer motor failed and I found that by breaking it open I could add a home made rubber washer (cut down grommet) and some light grease. This fixed it for 2 years when the plastic impellor snapped - £11 for the motor to fix it properly.
Also the Comms 2000 unit is a weird pig. Mine failed on fog lamps so I removed it and cleaned all the contacts and pushed all the little copper springs back a bit so they made more firm contacts. It really is a Heath Robnson of a device and it is no wonder they fail.
At 160k miles the contacts were very worn and the little copper springs extremely weak so I will be replacing it with a new one and keeping the old one for spares!
If you do the work yourself disconnect the battery before removing the airbag.