Bonjour monsieur
Have many 2465/7/A/B some with CTT.
Recommend
1/ post photos not video of symptoms, boards, etc
2/ post on both tekscopes2 and tekscopes, not the same
3/ get complete service manual for the exact type, options and serial number rangs, see W140, bama , etc.
Artech published excellent hard copies of the Tektronix manual
4/ follow trouble shoot flow chart
5 / see equipment list for full CAL
6/ check cables at edge of main board that connect at lower corners of CTT option board, easily overlooked
Bon chance
Jon
Froggie the Gremlin