Darryl Ramm wrote:
I always put a tape over the probe port when not in use to keep dust
out.

In my opinion, this requires a disclaimer. Nothing would ever happen to
Darryl's instruments, of course, but for the rest of us, if one has
expensive mechanical varios, one would be ill-advised to place tape or
any other airtight seals on the probe port. I don't think we need
another long thread on whether or why this is a problem, but based on
first-hand (expensive) experience, don't do it. I keep a collection of
vinyl caps (available from McMaster-Carr or any large hardware store)
that fit the probe port, each with a tiny hole in the center that I made
with a heated needle...

Marc