On Sunday, October 21, 2018 at 7:17:29 PM UTC-4, wrote:
I have a Tektronix 465B. I bought it used because it was one of the
scopes recommended by folks who post here and on the electronics basic
group. And I know hardly anything about oscilloscopes. It has worked
very well until two days ago. The volts/div switch has one position
where the display gets all wanky. I thinks that's the proper technical
term. When any other position is chosen on the switch the display
works perfectly. In the one bad position the display shows different
types of wankyness as I wiggle the selector knob slightly back and
forth. So I'm thinking about spraying some Deoxit D5 into the switch.
I'll probably need to remove the scope cover to do this. Is this a bad
idea? Is there a better solution?
Thanks,
Eric

Depending on the switch type, I use the following 'contact cleaners' from:
Caig - Deoxit
CRC contact cleaner
Chemtronics contact cleaner, cleaner&lube
LPS products

I will never let WD40 near any of my electronic stuff or mechanical stuff. Come to think of it, I don't let it near anything I work on.

For Tek scopes of that vintage, where lube is used, the original lube has dried out. After cleaning (to remove the dirt & oxidation, as well as the old lube), it is recommended to relube it. Its been a while since I did this and don't remember what I used, but IIRC, the Tek SM cited the product.

There is a tek scope NG. If you post your question on there, I am sure you will get excellent pointers.
Good luck
J