Hi All,  The question about whether or not to replace front rail
key bushings is one that most rebuilders deal with on a regular basis.
I have a simple rule of thumb that has served me well for many years:
"If there is any evidence of felt mite damage in the keybed, replace
all the felt."

Felt mite damage is easy to identify.  Just look for tiny holes in the
front rail felts and fine colored felt 'dust' under and/or around the
felts.  Felt mites seem to enjoy very soft felt like the front rail
felts.  However, they will migrate to harder or more dense felt over
time.  Once they migrate to the center rails felts, infestation is
considered severe and it is wise to treat the entire piano with a bug
bomb before completely dismantling the instrument.  Then replace all
the felt in the bed, including the key bushings.

If there is no evidence of felt mite damage, and the piano in question
belonged to me, I would have no hesitation about rotating the front
rail key pins to remove a small amount of undesirable side play.

On the other hand, if the piano belongs to a customer and the front
key bushings are relatively worn, I would discuss the matter with the
customer.  Having all of the key bushings professionally replaced costs
less than $150.00; Rochester Piano Key charges $70.00 per rail.

So, if you plan to use the instrument for many years to come, and the
felts are already fairly worn, replacing the bushings almost seems like
something you would want to consider doing as a matter of course.

Musically,
John A Tuttle
Player-Care.com
Brick, New Jersey, USA