Pleyel F3 bis hammers specs

[Stéphane Collin]

Hello dear list.

Does anyone know the original hammers specs for a Pleyel 3 bis piano (164 cm 
about 1900) ?  I would need to know the wood sort of the cores, the 
dimensions of bass and trebble felt shapes, the weight of the hammers and if 
there was underfelt (if yes how many layers of what stuff), in order to be 
able to have copies made.  Bore distance welcome, but I suppose I can 
calculate that from the piano.  Of great value would also be the originally 
intended strike distance.
I encountered a few of this amazing little piano (all great instruments), 
but those I worked on had the same problem : the hammers were rubbing 
against the backchecks (I mean the felt of the hammer knocking on the top of 
the backcheck when coming in rest position).  Of course, increasing hammer 
height would resolve the problem, but then the strike distance becomes way 
out of what I'm used to consider standard (45 - 47 mm).  Changing the 
backcheck angle could work, but you'd get a hard landing of the hammer tail 
on the backcheck leather, making noise and accelerating the wear process. 
Some other tech before chose brutaly to cut a wedge of felt out of each 
hammer.  I don't know why, I prefer thinking that the hammers specs are out 
of the ballpark.  That is why I'm asking.

Best regards.

Stéphane Collin