Hi Peter, Check to see if there is any water down in the plug holes.
Take out the plug leads and look down to the plugs with a torch, make sure there is no water around any of them. There was a concern with washer pipe leakage into that area. If there is, you will have to remove the cover and wipe out the moisture. doing it hot will help dry them up.
Reroute the washer pipe to effect the repair.
Paul
February 2008