Pianotech

This may seem to be a very dumb question, but bear with me.  For those of you out there who make new keyboards and may be in a position to know, I hope you can help me a bit.  The piano is a Steinway L from the mid 1920's.  

I have regulated many hundreds of Steinway grand actions over the decades and have rebuilt probably 150 Steinway grand actions, this one has an epic level of strangeness, and it is putting the fear in me that it may be unworkable.  In teardown, I made note of some serious anomalies.  The first thing I noted was that the back rail cloth was shimmed up to a thickness of 11 mm, and sitting at 22 mm. in relation to the keybed.  That is more than I have ever seen.  Secondly, the action stack was sitting lower than I have ever seen - the whippens were low by 4.8 mm, the shanks low by 3.1 mm.  I have reset the stack height on a great many Steinway grand actions, to good effect.  The factory spec is 146.1 mm. for shanks, 82.5 mm. for whips.  Resetting the stack height to those values, with maple shims, there was plenty of clearance for the drop screws and screw tops at the entrance.

I played with reproducing the overstuffed 11 mm. but it made the whippens sit too high in relation to the new stack height and test regulation was not kind to the feel and friction.  Hammers were bored to the existing string heights, which fall within normal values.  Capstan heels are at Steinway's height.  

I did reset the back rail cloth to a height of about 6 mm, but that is something of a stab in the dark, given the weirdness of this action.  The keyframe and keys are a very badly made set from about 40? years ago.  It is not a factory set of keys and frame.  There is a lot of warpage in the keys including along the length and there is twist in them and rubbing neighbors is a problem.  Very wide swings in humidity.

I have test regulated a number of keys at the ends and within the keyboard - knuckle/jack and capstan/heel friction is normal, promising a good result.  They feel good

Now, for the drum roll.  Even though the capstans are sitting at a height above the key that I would not call excessively high (meaning falling within a normal range of variability for a Steinway grand, en masse the capstans are sitting so high that, unrestrained the stack will literally sit on top of the capstans a few mm.  Unless I use guide pins temporarily sitting in the screw hole at the ends. I cannot position the stack in place.  I have never seen this in all the Steinway actions I have worked.  

There may be other weirdness in the keyframe that I have have missed, but I am beginning to suspect the possibility that this action stack may have come from a Steinway O instead of an L, because the shanks and whippens in relation to the capstans leave some fitting challenges.  

I pray for some pearls of wisdom from my sagely colleagues.