Robin,
Two things you look for, first is how far down the end of the male thread is from top of auto adjuster nut, if it is within 1/8" of the top or protruding then the band is worn out. I had to go and check a Ferret once where it was being shipped to Canada a day or so later, no 1st gear, the thread had come so far through the nut that there was a dent in the top cover! Well and truly worn out.
Right second thing you will notice if you are familiar with the boxes is how a worn band will sit lower than its neighbour.
Your friend Al, should study the EMER's until he understands the workings then go through the adjustments to the letter. The pedalling up procedure is often found to be more physical exercise for the driver than adjusting the bands, because the square head bolts that the pawl rides on are often out of range, so bands wear considerably without auto adjustment.
One of our forum members, Montie from South Africa with the Saracen had gearbox problems and after a number of emails to and fro, I asked him if we could talk on Skype. We arranged a time and he removed the cover off the box as instructed. While his mate held the camera on the box, Montie went through the gears and I was able to spot an adjustment problem in the gear engaging linkage. Once that was rectified and bus bar heights checked, I understand his problem was solved.
Hope this helps.
regards, Richard