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From: Wes on 15 Jul 2010 09:24
Recently, I reported that one of the keys on my calculator quit
functioning properly. It turned out that the problem was that the
tiny post under the key that presses against the dome switch was much
shorter than the posts under the other keys.

Somehow, I needed to lengthen the post. I thought of just putting a
drop of glue on the tip to lengthen it, but I wasn't sure how long
that would last. The posts are only about 1mm in diameter, so they're
too thin to glue an extension onto the tip. What I needed was some
sort of a sleeve to slide over the bad post. When I showed my wife
what I needed, she thought of a small craft bead. After trying some
that were too small or too big, we found one that had just the right
size hole and height.

I slid the craft bead over the short post, put a drop of super glue on
to hold it, waited overnight, and put it all back together. Success!
Works like a charm. The fixed key has ever-so-slightly less travel
than the other keys due to the now slightly longer post, but it's not
very noticeable.

A warning to future disassemblers: Someone mentioned that the
material that the keys are made from is a softer plastic to prevent
breakage. I was surprised just how soft the inner plastic is. When
replacing the screws, it is very easy to strip the threads or even
twist a screw post off. I used a razor blade to trim something inside
and I was surprised how easily the plastic cut. Just be careful.
With such soft plastic, maybe the short post really was just worn
down.

I don't know how long my repair job will last, but I delayed replacing
the whole calculator for at least a little while.

-wes
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