There was an article in a VW mag with the title = "Dead man's starter" regarding this problem, and according to the mag, it was caused = by either a poor ignition contact (as you already stated) or by the cogs not meshing properly. You can find out which it is by pushing = the van backwards for a couple of yards and trying to start it again. If it = starts, it's the cogs, if not then it's the ignition contact. I can't remember which = mag it was in, but I'm sure that's what it said.