[pianotech] Expanding leads

[David Love]

While I have run into expanding lead problems periodically generally they seem to have been reserved for "lesser" pianos.  Today I found a 1950's Boesendorfer 200 with leads expanding both in the back action and the keys to the extent that they were binding on their neighbors and on the verge of splitting things.  Of course I will have to remove and replace, a large task considering the new weigh-off at the key end that will be required.

My question is what is it that causes that reaction and why after such a time does it happen.  This is some 60 years later. 


David Love
www.davidlovepianos.com