I ran into the same problem today and initially came on here looking for the same answer. Having no luck I went back to my clippers and looked closer at the blades. At the far end where my clippers came into contact with the fence I found one of the blades was bent. Power was getting to the clippers but with a bent blade the moving part of the blades froze. A pair of pliers to bend back the damaged blade, plugged the clippers in and presto, it works.
Trev
August 2009