William Sommerwerck Inscribed thus:

How many caps need replacement? Why not just replace them and get it
over with?

These are also glued down !

Remember W Edwards Deming? "You cannot /inspect/ quality into a
product."

http://en.wikipedia.org/wiki/W._Edwards_Deming

Ceramic caps /ought/ to be reliable. The fact that even /one/ of these
has (apparently) failed, suggests the others are of questionable
quality. I'd replace all of them with high-grade caps.

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Best Regards:
Baron.