Ragu: Bonjour,
Search both TEKscopes at Groups.io and EEVblog as well.
Look for Tektronix cam switches/vert attenuators/7A29
1/ The PCB and atten modules are damaged by most cleaning INCLUDING deoxit, tuner cleaner as the PCB has polysolfone.
2/ We use ONLY 99% Isopropyl alcohol SPARINGLY, open up to expose the bifurcated switch fingers (DO NOT DISASSEMBLE CAM, SHAFT!) and use a clean lint free paper or business card, a drop of alchol.
3/ NEVER use any oil, petroleum product Deoxit, etc to "lubricate" the cam switch's do no need it and the contacts will be contaminated.
Bon Chance
Jon
Froggie the Gremlin