My "new" 1954 CTC2B 21CT55 21" roundie

[Electronic M]

Dang! I wish I had the kinda luck and friends you've got.

In your shoes I'd pull the deflection output tubes, put a meter the high B+ rail, and variac it up till that B+ rail reaches spec, or signs of trouble appear. If it goes good scope the Horizontal osc. If that is good reinstall the sweep tubes, and power it up while monitoring cathode current of the H out tube (the schematic should be on the ETF's site and should give you the safe max cathode current spec).

I don't know of a more desirable 21" color set. The 21CT55 was the first of them....Built in response to other companies coming out with 19" CRT loosely based on the 15GP, but containing many new innovations the 15G lacked....That and when a customer shells out what one of those cost they want the biggest screen they can get.