After further replacing the hammer spring (no improvement) and then finally the firing pin itself, I saw the problem through to a successful conclusion, she now reliably lights off whatever is shoved in her two chambers, Hornadys, CCIs Winchesters, Federals, whatever. And, I learned a great deal more then I previously knew about the innards of a High Standard DM101 along the way, and learning stuff is good.
Heck, I even ran across a slick pair of checkered walnut stocks for the little bugger that make the nickled finish look really nice. Hope I can blunder into a pretty little Null belt holster like RichCapeCod has, that would be quite a nice little set up!
Thanks to all that offered advice!