Twice the bodies were somewhat hollow in two baits, different injections. Same cavity, nearest the hinge.
I'm thinking the mold will want to be injected while the mold itself is pretty warm. That cavity nearest the hinge is likely not getting as warm as the other because of all the extra metal with the hinge.
I tried plastic at a bunch of different temps, 280 all the way up to 430.
If time allows, I'm going to heat the hinge end of the mold up to where its pretty hot to touch and try that. Also, on the cavity furthest from the hinge, the eye on one side [facing down] does not fill completely. That doesn't bother me much as I'll use other colors to make eyes if I want them. And in studying the baits I've shot and looking at the mold and sprue area, I think the sprue needs to be larger in diameter to allow more plastic in the cavity during the injection.