Hi Bryan
I had a similar situation with my handbrake cable and trying to adjust it up sufficiently to give a maximum of 3 clicks to be on. I could not get the handbrake to be very effective and the adjustment was right up with nowhere else to go. I thought I'd got the wrong cable, perhaps the brake adjusters were out, but I couldn't suss it. I then went back to the start and checked the whole cable installation from the beginning and opened up the inspection plate on the tunnel in the rear of the cabin and there it was, having checked back all the way from the lever into the drum back plates, all fixings and clamps only to find the outer cable flange was not seated in the through hole in the tunnel at the rear correctly, so the cable had nothing to adjust against. Once fitted correctly, there was plenty of adjustment available and it set up perfectly. It now only has 1 click and is on as solid as a solid thing, works great. It's a daft thing really but it had me flummoxed for a while. Just a thought for you.
Cheers
Hugh Jarce (aka Gary)