The 10811 that I have has a decal on it that reads "upgraded to series
3010". Do you know what that means?

Lefty-

The 10811-60111 that came in my used HP 5334B counter, had a blown thermal
fuse. Upon considerable investigation, I found that it was a common problem
and had been addressed by HP, using fuse with a higher temperature rating. It
is possible that your 3010 refers to the thermal fuse upgrade.

Incidentally, the going price for a used 10811-60111 was around $100 a couple
of years ago. I trusted a guy and ended up with a second unit that also had a
blown thermal fuse!

73, Fred, K4DII