Steinway sostenuto nightmare

[David Nereson]

    Usually I take pride in being able to get a poorly-functioning 
Steinway sostenuto blade adjusted properly.  But today I had one that 
consumed 3 hours and still had me baffled.  I did manage to get it so 
that, working the sost. pedal by itself, it doesn't catch any tabs 
(doesn't lift any dampers).  And after depressing the damper pedal, then 
the sost. pedal, it holds all the dampers up off the strings.  However, 
keys that are played after depressing the sost. pedal hang up and stick 
on the blade.  They shouldn't; they should return and damp the string 
since those keys weren't depressed before the pedal was engaged.  But if 
I pull the blade back in towards the action even 1/32",  it doesn't 
catch any tabs at all -- it lets them all drop!  Aarrrggghhh!
    The in-out adjustment of the blade is extremely critical -- more so 
than usual.  I found that many of the sost. tabs were not in a straight 
line, looking down from the top, which required pushing in or pulling 
out on the damper wire (slightly), to make the sostenuto tabs sit 
farther back or farther forward. 
    There's no stop screw for the pedal.  There is a stop pad, but it 
was allowing too much travel in the pedal so that the sostenuto blade 
acted like a damper pedal -- lifting them all off the strings!  Also the 
monkey hangs down below the bottom of the keyframe and rubs across the 
keybed when the action is pulled out.  The bottom of the monkey pokes 
down into the pitman hole, so when the action is pulled out, it catches 
in the hole and the spring gets ripped out of its slot in the monkey.  
    Shouldn't the monkey, at rest, clear the keybed?  If so, what keeps 
it up there?  (The spring is pressing it down).   Can the square loop of 
wire that hooks into the monkey be bent to make the blade point farther 
down (or up) when at rest?  It seems the blade doesn't go down far 
enough when at rest (pedal released), because the top of the monkey hits 
the rod, preventing any further return.
    The blade also sits too close to the level of the sostenuto tabs.  I 
tried lowering it by removing punchings from the rear bracket screws and 
adding to the front screw, pointing the the whole bracket/blade assembly 
down, but this can't be done too extremely or the damper levers will 
then clank on the blade.  Not too long ago, someone on this list had a 
similar problem and tried to bend the brackets down,  but they broke 
since they're cast brass, not strap iron or steel, I believe.  I would 
look for that thread, but everyone's been complaining of archive search 
problems. 
    I thought of re-regulating the dampers so the tabs (damper-wire 
blocks) all sit higher, but the dampers are already regulated to lift 
quite late in the key stroke and I don't want to make them any later.
    This piano (approx. 20 years old)  was purchased by the present 
owner at the Steinway showroom in New York and supposedly has never been 
messed with.  But I almost couldn't get the action out because the 
hammer flange screws were scraping the pinblock so hard.  Had to turn 
the glide studs up just to remove the action!  Even with studs turned 
up, the screw-to-pinblock clearance was barely 1/16".  No evidence of 
any major warpage or bowing in the pinblock, keyframe, or keybed.
    --Stumped,    David Nereson, RPT