Well number one, give Grizzly a call for the rest of the parts you need. Before you put those parts in though check out the spindle and drive closely to make sure they are not stiff or seizing. Then write a kind letter of displeasure to the president of Grizzly. That should get you running.Any help or suggestions appreciated. I want to get this thing running reliably so that I can CNC it.
As to CNCing your machine long term consider a better motor and drive. If you build a controller make sure you leave provision for such a drive. There seems to be a real quality issue with these motor drive combos. That is sad considering how nice the machine is mechanically. Thankfully good quality American made drives aren't that expensive. Beyond that CNCing may benefit from an easily controlled drive.