The Sport Mechanic and Recreational stands use the Spinner Knob Cam Pocket Part no.15684

The Cam Pocket can be removed without removing the clamp from the stand

Remove clamp from head by unscrewing completely Use a flat prying tool to remove cam pocket
Cam Pocket it now removableRemove cam pocket
Install new cam pocketTap with hammer until it clicks into place and reinstall clamp by threading it back into the head