Call me late to the party, but Dad's (incomplete) Sams for the CTC11 is marked up pretty good. There's this (
not in Dad's handwriting) -
HOT cherries, check Osc tube filament for 6V. Was half. No corrective action listed.
And plenty about contrast, swapping guns to check CRT, and other non-germane stuff.
PF Reporter also had an instance...
http://www.americanradiohistory.com/...rch=%226dq5%22
Me, no experience earlier than a CTC12, so no real help beyond that note..