Instead of mating your pivot with a concentric mate, try a tangent mate. This will allow the pivot boss to follow the wall of the mating pivot hole and provide for some lash.
In one situation I did a distance mate between the axis of the otherwise concentric axis' that was offset by the max tolerance of my parts. It makes the movement very jumpy and can be hard to control, but it gives the full range of possible movement for a linkage.
The two ideas can work (with some movement problems). but which one the best for a serial robot.