I agree that there could be a leak in a fuel line that is routed through the rigging tube but there could also be a leak that causes fuel to pool in the lower cowl and drains out when the motor is tilted up. One simple test I might try is to tilt the motor up, make sure the motor well is dry and pump the heck out of the primer bulb. Note if the bulb is firm to start. If not there may be a leak between it and the fuel pump. After pumping the bulb look/smell for leakage.
Since the fuel lines upstream(towards the tank) of the fuel pump are under lower pressure when the motor is running than when sitting, you usually don't see more leakage when running. I don't know what on motor fuel filter you have but if it is the removable clear bowl type, check that for leakage especially after pumping the primer.
If you have a leak in the fuel hose between the tank and the primer bulb, that is a bit harder to isolate. One way other than removing and inspecting the hose is to install a second primer bulb between the tank pickup and the fuel hose,. Pumping that should result in a firm bulb that holds pressure. If there is a leak, the pressure will drop and you should see/smell fuel.