Have maxed centurian but game doesn't recognize or allow me to cycle through to tractor beam. Any thoughts on how to correct this?

Maxed Centurion? What and how? Four forward guns, two missile launchers, turret with two guns and tractor beam (on this turret)? That's my config...

If you have only one missile/torpedo launcher and tractor beam instead of second launcher then use "w" key to switch between launcher and TB. Use it by pressing "Enter" key.

If you have two launchers and TB on turret then you must switch view to turret and then use TB. My way to deal with such config is:
1) track and lock target ("l" key; small "L", without shift),
2) fast switch to turret view ("F5" key) and hit "Enter" key,
3) fast switch to cockpit view ("F1" key),
4) point your ship to you target which is "beamed" with blue ray.
Make sure target is within 2k clicks or TB will have problems with it. Time is important too.