Too much slip

[What's_nitro?]

It shouldn't be slipping much at all when it's tightened down.

I'll ask a silly, but relevant, question: Were there any parts left when you finished assembling the unit?

Can you take a side-on picture showing how the parts are arranged, just to confirm the unit is assembled correctly?

I believe the axial relationship of the springs can affect how much pressure they apply. They have to be lined up with each other a certain way.