I received an e mail from Ruger, announcing the Ruger replacement trigger assembly.
It is the BX trigger unit.
As the cost is $89.00, I ordered one, received it, installed it (easy), and it works just fine.
Trigger pull measures 3#5 ounces, and is very crisp.
It is available from the Ruger shopping website.
It is in my 10-22 take down, which used to measure 6-7 #.
I have a very old 10-22, (45 years +) but as its trigger is great, I won't replace it.