I think John Phillips's piano tuner must have been having a bad day. I
cannot believe that the correct hammer travel on the Steck/Weber is
close to 1 inch. Reblitz (p. 65) gives the hammer stroke on old
uprights as 1 3/4", and my old English upright has a hammer travel of
2", having never been rehammered.
John goes on the say he has set the hammer-check position but makes no
mention of setting the hammer letoff. This is where his problem with
the bubbling note lies. The jack on the offending note is not letting
off, and the hammer is bouncing back and forth between the string and
the top of the jack. For this job he will need the correct tool.
I suggest that John put the hammer travel back to where it was and then
regulate the entire action according Reblitz's instructions in his
book, "Piano Servicing, Tuning and Rebuilding," after buying a full set
of piano action tools (not cheap!). Good luck to John.