Leaking in PRI and stops on Reserve?
First of all the "normal" running positions for the petc0ck is either On or Res, because they are vacuum operated.
PRI is for maintenance or to fill an empty carb with gas after working on it. PRI is an "always on" position, so if there is a carb float problem (as mentioned above) this would be the most likely way to find out
It can be your float setting, the float needle valve, dirt in the carb, or a leaking gasket. Need to drop the bowl off....
As for the upside down picture....that looks like the brake pedal switch in the lower corner...and I don't think they usually leak gas....(just kidding)
....that large hose is your airbox drain. Just for grins, pull the plug on the end of that hose and see what comes out.