Any piano will not play properly if the centre pins are stiff in their
bushings.  There are about 330 centre pins in the action of an upright
piano and even more in a grand piano.

Repinning is hardly a task a hobbyist can do properly, for lack of
tools, materials, and above all, technique, which can only come from
a lot of experience.

While some chemical treatments can work sometimes, again, experience
and knowledge are required to know how, what, where, when.

Chances are, if there are problems with the centre pins, (too stiff
or too loose) there are other problems with the action as well (e.g.,
worn hammer, damper, wippen and key felts, corrosion of metal parts,
regulation, etc.).

Do yourself and your piano a favour -- call in a qualified piano
technician.  As with so many repair/restoration jobs, it will be
cheaper to have a professional do the job from the start than to
call them in after it has been botched by a lay person.  The piano
rebuilding book by Reblitz is excellent, but I see it as more of
a reference book or training manual to the profession of piano
technicians than a guide for do-it-yourselfers.

Jurgen Goering - piano technician
Vancouver Island, BC, Canada