I’m not super familiar with the 587 motors, but the first and easiest thing I would try is to trim the plug wires back a bit. If they are the same as the later motors, you can unscrew the plug terminal and snip the wire back 1/4” and then reinstall the terminal. I can’t imagine both plug wires would be bad at the same time, but that’s a quick, easy, and free place to start. If that doesn’t lead anywhere, you’re going to want to dig into the service manual and start troubleshooting on the coil and all of the related wiring.