"Doesn't change the fact that at least two of us still seek
a solution. "

True, but realize that some newsreaders have this thread waaaaaaay down at the bottom of a very long list. I see you use gmail, so do I. When you post a reply gmail brings it up to the top. This is not always so with people who use other methods of access. To get to the maximum number of people it is better to start a new thread, after seeing if any of the links are good in the old one of course.

It is a bit surprising that there is still a print available via that link. If you see an old post like this and a link is to a tinypic or an imageshack, it is not likely to still be there. Russian (.ru) links seem to stay put, possibly because they are not a throwaway society and keep things running, instead of dumping everything in a landfill every two years.

Anyway, according to the print, current sensing is done by R15. Anythng wrong with N2 or its associated circuitry could be at fault.

Question, what does the current meter read ? Is it zero or does it read a bunch of current ? It could be as simple as something shorted across the output terminals.

I assume the constant current LED is lit, if you turn the voltage all the way down does it switch to the constant voltage LED ?