Always when you get a flooding carb first thing to do is check the needle valve / floats as this is the most probable cause.

I also had a same problem with mine after it had been standing for few months. After carefully removing the carb top / floats and taking the needle valve apart and cleaning it (just blowing it really) and checking the float levels the problem was gone. I don't use return neither, altho my fuel pump is mechanical.

-EDIT- Only thing that sounds little weird for me is that you said it was leaking from the bottom. When my carbs flood they leak from the top. But since you have the DCOM model vs. my DCOE which I believe use the "DHLA style" diaphragm pump circuit I dunno if this makes a difference regarding what would be the first place to leak then. I would still check the needle valves/floats since it's a easy job to do.