Hi Andries & Paul
Thanks for all the info. From your detailed description Andries and the very clear diagrams Paul sent, I now feel quite confident to carry out the repair.
It's amazing, I have been searching for this info for weeks, not thinking it was important enough to raise a new thread in the forum. Having seen Metalhackers indirect reference, some years ago, to the problem, I thought it might be worth asking for help and within 2 days, I had exactly the info I was looking for.
Thanks again and in future, I will be more courageous in asking for help! I like to think I should be able to these things without bothering other people.
Bill