Thanks for replying. Yes it is supposed to be a threaded hole, but it isn't! Have you fitted one of these ladders? No one even at Youngmans knows how to do this. Sounds to me as if something should be staying in place and not dropping down but of course it is all internal and we can't find a cross diagram. Was prepared to think I had a faulty ladder to start with as the box had been tampered with, but it was exchanged for a properly packed one and the same thing happened as I removed the arm. I took it back for a refund but this is a good ladder and if I could find out where it is going wrong, I would buy yet a third one. On one website, a user said beware the fixing falling into the ladder, but no more than that......