Center Pin Question

[Thomas Cole]

I have a piano in the shop which is being prepped for sale. It happens 
to be a Wurlitzer model 200A electric piano, low miles but the action 
was a little sluggish and I couldn't regulate it because of tight 
centers. I've repinned and Goose-juiced hammer and wippen flanges and 
noticed that all of the center pins had a blue-green coating on the ends.

I've been monitoring the Wurlitzer Electric Piano list and some people 
are saying yes, use silicone to free up the action and others are saying 
that piano techs recommend against silicone. Didn't Wurlitzer recommend 
using silicone / naphtha to lube the centers? Has anyone noticed a 
similar verdigris problem on Wurlitzers or other non-Steinway pianos? 
What would cause such a corrosion?

Thanks,
Tom Cole