Material Bay Drive Motor Issue - Filament Obstruction
When you are having trouble loading materials and the drive motor on the material bay does not engage when you place the spool into the material bay, the first thing you should check is your materials screen.
With the spool and filament unloaded and removed from the bay, the materials screen should display a grayed out section like this:
Problems may occur if a piece of filament breaks from the spool and becomes dislodged on the filament path. If this is the case you'll notice a small blue indication on the path between the bay and the head:
If this occurs, you could using a section of filament from the spool to dislodge the stuck piece.
Manually feeding filament through the filament path to the head is the next troubleshooting step. If the filament can reach the head you should be able to "Load" the material through the menu.
If you cannot reach the head, than the filament path is being blocked and you'll need to investigate the issue further.