I have this old squirrel cage induction motor (nameplate below) that I just replaced the bearings on. When it runs, there is a rattling noise that gradually gets louder and then softer, repeating every ~5 seconds. Here's a video of it in action. I don't think the motor made this noise before replacing the bearings, but I'm not sure. (I just bought it and the only time I ran it was briefly at the seller's house.) Does anybody know what might be the source of this rattle? I've put pictures of the motor and the rotor below, as well. Thanks!