I found that bung to be the only weak link in the design......I usually cover mine up with a very small amount of gaffer tape just cut big enough to cover socket.....
Did you buy it as a 2012 dash mate? :S I am confused as the 2012 HM Dash defo uses the rotary switch for gear position, I checked it out on HM's bike when I was at HM Racing's dyno last. You'd have to talk to HM about that as they would know why... unless the one I played with was a prototype?