I used to work on tons of these sets, and must say if working right, they produced a really good picture, although it did sort of look like viewing the picture though a screen, due to the size of the pixels of the CRT.

A way to roughly date sets is with date codes. The filter can
seems to be the best ( if it hasnt been changed).
Look for 4 digit numbers, if it says 2368 it was made the
23rd week of 1968 add a few months to that. See if you can
find others marked that way. Unfortunately there are other
date schemes that are unreadable. Also look up the
MODEL number in Sams. They come out abt a year later.

73 Zeno