I suppose it all depends on how old the set is (if you have a 1920’s Atwater Kent breadboard, you might want to restuff the wax capacitors), what you intend to do with the radio (is it going to be a daily listener?) and whether one or more people mucked-about with the set before you acquired it.
A case in point is the Toronto-built 1947 Stromberg-Carlson 694 I acquired a couple years ago.
I farmed-out the repairs on this set to an electronics engineer friend in Georgia, at first because the cabinet was rough. My engineer friend also has a completely equipped woodworking and finishing shop, and I am a wood butcher.
As it turned out, the electronics needed more TLC than the cabinet. Someone had replaced the four knobs with examples that appeared to have come off a piece of Heathkit test equipment. I located some Rochester Stromberg knobs which now grace the radio. They might not be original to this set, but at least they are S-C.
There was supposed to be a tuning eye in the middle of the dial. The 6U5 and its bracket were missing and had been replaced with a large translucent marble, the size of a big shooter, glued to the dial. Since the likelihood of finding a replacement bracket was nil, my friend had to fabricate one for a N.O.S. 6U5 I supplied.
Since his fabricated bracket interfered with a can-type electrolytic (which was bad, anyway), my friend wound up milling-out the hole and replacing it with a shorter, but fatter, N.O.S. Mallory. This has since expired itself, BTW, so I will need to order a new production cap from Hayseed Hamfest.
The voice coil on the 694’s 8″ PM speaker was shot, so my friend replaced the speaker with a Pioneer 8″ co-axial speaker. This was not overkill, as the set has an RCA phono jack, selected by one of the pushbuttons under the dial. When the “phono” button is depressed, whatever is connected to the jack is linked directly to the audio circuitry and its push-pull 6L6’s and decent sized output transformer.
An FM tuner or CD player sounds great on the 694!
Several resistors had been replaced with ones of incorrect values — so far off from what was called for on the schematic than they couldn’t have been factory production changes.
Finally, the insanely complex dial mechanism had to be restrung.
When returning the set to me, my friend included a note, “If you ever have to restring this dial, call 911!”