I'd assume that there is some sort of infertility going on as they should have produced by now I would think. Do you see the male chasing the females around. This chasing is a necessary part of their mating rituals and some females will not stand to breed if he doesn't chase them first.
If he's the issue trying to put in a new male likely won't work so you may have to feed off the whole group. You can try a new male in there but the resident females may kill him. If you do want to try a new male, remove some of the females stinky bedding from the enclosure and put him in a very small container with it for a couple of hours. That may transfer enough colony scent to keep him safe from the females.
For the other colony, raising up one of their own male offspring is the safest bet. It puts you a bit behind on production but it's the safest way to bring a fertile male back into that group of females.