You need a star type lick washer (internal or external, with internal a little better) to make sure a solid bond is formed that cuts trough paint and any contamination on the surface.

Thanks for his reply. Let me add some clarification, as I'm afraid my initial post was unclear. The old motor had a ground wire running from the case of the motor to a universal grounding bar on the panel (where other components were grounded as well). The new motor has no grounding connection at all. Does that mean none is required? I am not talking about the grounding of the entire spa - that is still intact. I'm talking specifically about the grounding of the small motor that runs the circulation pump. Hope that's clear! And again, thanks in advance.

"Does that mean none is required?"

No.
It needs to be bonded just like the old motor.

This isn't the ground, it's the equipotential bonding required of all components and exposed metal of the spa. If something doesn't have a bonding terminal, you must install one.

"This isn't the ground, it's the equipotential bonding required of all components and exposed metal of the spa. "

It follows the same rules for how the bond connection is to be made.

I wasn't arguing with you brick. It is NOT a ground. The requirement for it is different than for grounding (but the terminal is the same as you say). All the things required to be bonded need to be bonded with #8 solid.