The sinks are touching the large coils, but there is some plastic between:
http://www.nskjaer.dk/antec/cwdata/antec40.html
The white stuff is doublesided tape and you can see some of the plastic.
But what about conductive electricity? Could that be the problem?
Tomorrow I will take it apart and replace the mica shims and the screws with nylon screws, that way I should be certain that there is no connection between the mosfets and the sinks.