Not expensive to replace.
Source one first:
Spares suppliers:
www.4directelectricals.co.uk
http://www.ukwhitegoods.co.uk
http://www.domesticspares.co.uk
http://shop.ezee-fix.co.uk
or simply go into google and type in "washing machine spare parts" - selecting "pages from uk".
If you are familiar with ebay, there are dozens of sellers running washing machine spare parts shops at very competitive prices.
Remove machine covers, power off of course, interlock usually held in with couple of screws. Swap wires over one at a time from old to new unit and refix with screws.
Repair and service your own washing machine. Go to www.2ndwave.co.uk/manual.html
dannyboy
October 2008