Hi Stu
Good idea, varistream have the MK2.5 version out now, and its something to do with the switch.
I also read a post on here last week (I think) and someone said it was a small dab of silicon or glue that causes the problem, once this is cleaned it works as normal again.
The silicon gell idea for varistreams protection of the PCB,
I think its a good idea, it helps keep the damp from the Boards, so I would highly recommend them. Good Post.