In the end I called a plumber
A while back I posted about my troubles trying to solder 1 1/4 copper in a heating system that I couldn’t get dry. I tried nearly all of the helpful suggestions, pressurized the system one last time, only to see water squirting out of one of my inadequately sweated joints. So, I swallowed my pride and called a plumber. Good move on my part, and once again I was reminded of the big difference between an experienced DIY-er (me) and a professional. The thing is, I have considerable experience with 1/2 and 3/4 copper, but not with 1 1/4. It was a revelation watching him work those joints, moving the torch around, adding dabs of flux, more solder, taking great care to see that the joint was good all around. His bill was very reasonable and worth every penny.
So, should I have contracted out this job to begin with? When does a DIYer know he is in over his head? There is probably no general answer to this problem, as every problem is different.