The bearings are shot and all the amount of cleaning, oil and grease will not help. It might be quiet for an hour or so but it will start up again. It is most likely the bearing closest to the drum. While you have it apart the drum fan needs to come out with it. Thirty years on it might be a bitch to remove it from the motor shaft. If it is tough, a puller may be needed to get it off. You'll also notice that the fins of the drum are probably full of crud which impedes air flow and they should be scraped clean.
A possibility is something got wedge in (paper or plastic) the blower housing and it is rubbing on the blower itself. A funny story, my neightbor had a noise coming from his Jeep when the AC blower was on. He didn't believe me but I did prove to home, we found a piece of cellophane from a tape cassette had been sucked in and it was making a racket inside the squirrel cage.