Dobs, how hot do you heat your plastic? I heat mine up to 350 degrees and ALWAYS have trouble with a duel injector and the blending block. It is very common to get no good baits! The way I do it now is to hand pour the top, close the mold and inject the bottom. I would like to be able to do it the way he does in the films.
I always heat my injector and block but stay below 320 or so after the initial heat with my plastic. That said, keeping everything hot, I can shoot a lot of plastic through my dual injector. I also reheat my injector after demolding and use a propane torch on the injectors and blending block. I try to shoot 8-10 multi cavity molds at a time. That’s what works for me.