if they are frozen will they still turn freely?
The mechanism that engages the locker is spring-loaded. If that mechanism is full of dirt, a mixture of dirt and grease or frozen water, the spring loading won't release and the axle shaft will not engage with the hub when you turn the locking knob.
A good cleaning up will usually sove the problem. Do a search for
locking hub at Ack's FAQ (link in sig below) for info on how to rebuild/clean your Asin locking hubs.
You can swap hubs between Samurais as they had the same locking hubs thoughout their US production run.
Such is not the always case between Samurais and TracKicks as there is a slight difference between the locking hubs for each type of vehicle.
Hope this helps!