you need to check the plugs with some airpressure. spray some soapy water onto the epoxied plugs and shoot the air through the jet orifices. Check both sets of plugs. btw, not all epoxies are created equal, most have agreed on this forum that marine-tex epoxy is the way to go BUT... first tap the plugs holes and insert some type of threaded plug (small set screws work in some cases) and use the epoxy to keep them in place (kinda like thread lock).
Devcon also makes a good epoxy that is fuel resistant.
Other than the plugs i cannot think of why fuel would be leaking by the pass side primary (unless there are cracks, again, check with soapy water and air pressure.
another thing could be the fitment of the main body and baseplate but i am wondering how the fuel could do that since the only circuit that transverses the base plate is the idle circuit and it has to go up above the fuel level before it comes back down. (kinda rules that out)
The accel pump circuit also has a plug on the bottom on the pass side somewhat.....
(Needle/seat gasket sealing issues??? I dont think so cause it would jus drain back into the line)
Ok, that s all I can think of, hope some of this will help!?? (at least tis a start) good luck!!