Steinway hammer shape

[Bec and John]

Hi,

I read a post from a while back where someone was talking about 
reshaping/filing/etc. a Steinway hammer "the way Steinway says to", or 
something to that effect. However, they didn't describe what that way 
is.

Over the past week or so, I'm seeing (hearing) that my piano's hammers 
need reshaping, and before I go about that I thought I'd ask if anyone 
knows what the "Steinway" shape is supposed to be.

Also, the highest hammers have deep grooves in them and I didn't want 
to file them too much in order to remove the grooves, but soft pedal 
usage makes the tone "disappear" (the un-grooved spots are soft). How 
much filing can be done on those highest hammers?

Thanks.

- John