Not sure what thing a ma jig you are referring to. There are a number of threads on the smell (most likely gas) coming from the car. The two small vent lines next to the fuel filler neck, old, plugged hoses from those vents, plugs in the vents themselves, cracks in the small vent tank in the fender well, all can contribute to the gas smell.
Use the search feature, gas smell, might be a good place to start to get the details on how to deal with this. When I first got my car, the smell was a problem. I found the two small vent holes plugged as well as the metal and rubber lines to the vent tank.
Jonny B
1967 250SL Auto