James Sweet wrote:

The 485 is a really excellent scope, and the problem you describe should be
fairly easy to repair. There's no sense in upgrading, as a beginner you
probably won't use a large portion of the features the 485 provides even.

Agreed, and I bet a nickel the issue is that there is too much dust and
dirt providing leakage paths in the high voltage section. Have the tech
give it a good cleaning and you will probably be fine.

I'm still using a Tek tube scope at work and it's always been flawless
although the calibration guys hate me.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."