On 07/24/2014 08:14 PM, Chris B. wrote:

about 100 ohms.

I'd just like to have an idea of what the problem might be before I
change any more components. Now I'm half wondering if it's the IC and
the fact that it's facing up and has a fan on it is allowing it to
work properly. Anyway, thanks for reading my long story and I'd
appreciate any suggestions you have.

This is where I downloaded the service manual:

http://elektrotanya.com/tektronix_22.../download.html

The problem is you bought the scope without the manual that should
accompany it as it travels through life. I lucked out and got my $225
465 from a Tek sales rep/ham. The 2" thick manual includes all repairs,
upgrades, part substitutions, liner notes, etc. In a perfect world the
manual travels with the device.