Sure, there must be a complex mechanism inside to keep the cylinder in place.
I agree with you about the value of knowledge. In fact I went to the locksmith to buy the new cylinder. I thought that selling me that cylinder at 30-40 euro was his reward for telling me something more about that screw. I could go to a diy store and get the same cylinder for 20 euro, or waiting 2 weeks and buy it on ebay for 10 euro.
Anyway he made his choice and earned more. I understand his point of view. I had my cylinder changed without damaging the door, that could have happened to me, so I'm happy too.
I was just hoping for a better deal for both of us, me and him.
Cheers
