Blower motor - replaced, but locked up/buzzing when on?

Hi y'all, Our air wasn't blowing, so I changed the capacitor, didn't fix it. It's a old (30+ yr) unit, so I assumed it was the blower motor. I bought a replacement and installed today. One of the mounting fins was a little bent in shipping, but I bent it back. Got it in, screwed everything down, gave the fan a couple spins to make sure it rotates, started it up ... and just buzzing. Interestingly enough, the fan doesn't spin when the motor is on/buzzing. Any ideas?

Thanks in advance