Aircooled VW main jet missing?

Ok, the main jet is located behind a brass plug on the little gas holding tank behind the carb... correct? Well, I took out the plug and then went after the jet and my screwdriver went right into the tank!! There was no jet at that location, have you ever heard of it being somewhere else? This is on a 74 Thing. I have no recollection of taking out the jet and the Thing ran the last time I tried it..... fairies?