I think the non-potted controllers can get wet and fail. All new ones are potted, although I have had a worrying number of people (about five) have this problem. PM me your address and i'll get a replacement to you in the next week or so.
Thanks Tom,
I'm sure from memory mine is in the sealed black box. I guess I'll find out when I have to rip it out again !
cheers, I'll PM you my address shortly