Regarding banana plug use here's what is says in the manual:

"Before using banana type jacks make certain that the plastic screw caps are firmly tightened down by turning them
in a counter clockwise direction until they are snug against the chassis. This will insure that the maximum surface area of the plug is in contact with the jack."

Counter clockwise loosens the the screw cap. Shouldn't it read "turn clockwise"?

That said counter clockwise would present more metal surface for the banana plug to anchor onto. The screw cap is brass lined.