Duncan's 1960 Magnavox

[Electronic M]

Only lytics and IIRC Tantalums are polarized.

Your flyback is probably fine if it makes the screen light up that well. Many flys would normally drip some wax or tar (depending on what they're made of) over the course of their service life....It's also not uncommon for some of the tar to chip or peel off with age....the flyback doesn't need replaced it just needs recoating with wax, tar, corona dope or sensor safe RTV (which one is a matter of personal preference).

The positive grounded lytic probably filters a negative voltage rail. All tube gear has positive rails, but some have negative rails too. Some sets connect the can lytic capacitor negatives to a floating negative rail separate from the chassis, and if you change that bad results tend to occur. Another thing that can be confusing when you see it for the first time is a voltage doubler circuit.

Don't replace paper caps with ceramics in TVs, ceramics aren't stable enough for video and sweep applications that originally called for paper.