1989 Ford F-150 Key cylinder won't engage starter

This is very similar to a message a few days ago regarding ignition switch.

The switch seems to work in each position, but the key cylinder does not engage starter or return from the "start" position.

Is this likely the switch or the device that attaches to the rod going from the key cylinder to the switch?

If the latter, how do you replace it - possible part # 3E717?

Thanks.