Well, I think it needs more than a cleaning of the contacts. It definitely sounds more than a bit iffy when it doesn't work properly (which isn't all the time at least).
Looks like the poor little chap's off to the lens hospital.

Still, it's not done bad I suppose, it's had a bit of a hammering over the five years, being out in all weathers, long night exposures, long day exposures in the sea and the rain... mustn't grumble... grrrr.

What I really can't forgive though is that the first time it happened was whilst taking a pic of Colin's Nikon D7000 in London :o/ Dark-side indeed!

London: