There is a product available from piano supply houses, called
Lunsford-Alden "Pin-Tite".  The piano is placed on its back and drops
of this liquid are put in around the tuning pins, until the wood will
not absorb any more liquid.  This liquid swells the wood and usually
will improve the tuning stability.  I have used this product and have
had good results.

There are purists who shun this treatment, but if the piano is useless
as it is, why not give it a try?

Bruce Clark