Removing Fuel Dist.

I'm trying to clean the throttle body on my 88 300E, because there is a bunch of dirt and grime inside it. I have already undone most of the screws holding the throttle body down, but I need to remove the fuel distributor. The screws that hold the fuel distributor onto the throttle body appear as if they need to be removed with an allen head wrench. I have used a 3mm and 4mm allen head and the 3mm is to small and the 4mm is to large. I assume I need a 3.5mm allen head wrench, but I haven't been able to find one anywhere. If anyone has any recommendations on what I should do or if anyone knows where to get a 3.5mm allen head I would appreciate it?