My 350z compression arm won't tighten it just keeps free spinning. I Don't think the ball joint itself is broken because the owner before me just replaced it. Anyone have had this problem before and have found a solution? thanks in advance

 

The stud will be a taper fit, you’ll need to apply some load to it by prying it into its hole, the tightening.

 

I used tape measure around my arm to see what the recommended size was, the sleeve should show you what arm size equates to S/M/L on the listing. It should not be cutting off blood flow, it should be just a bit snug on your arm so it
doesn't flop around or slide off.