Okay, that's the parts done. I've opted for an open ratchet so that the curious user can see what is going on. Hopefully the you can see what is happening in the picture above. The housing, containing the pawl (with magnified picture, top right) rocks back and forth advancing the gear one tooth at a time as it does so. The two stops are there to constraint the movement. I'll be putting together a final test piece as I've made a couple of small changes to sizes then it'll be onwards with colour and final layout. Not long now!