Thanks for your advice, I will take it in eventually.
I really suppose the underlying problem is that all these problems have undermined my confidence completely.
There I was happily using what lessons I had learned with sterling silver, doing my own thing, and getting on, only needing the teachers advice occasionally. Feeling I could handle just about anything now, and then I hit this catastrophe...nothing works,uHaving to go over and over the same steps with limited success. It was a shock to the system...and reinforces the idea that I shouldn't believe everything I see on YouTube!
From all this discussion, I now feel like I am back at the very beginning. But I am a stubborn person and I will persist. I have invested a fair amount in buying Argentium wire, sheet and solder, so I need to use it. Other people seem to have no problems at all, so in the end it must be me. Practice, practice, practice as the old saying goes. I will document my next piece very thoroughly, and perhaps find an answer to my problem.
Warm regards and thanks for all the advice,