How do you adjust the parking brake on the JL8 rear disc option. I am not talking about at the cable but at the rear calipers themselves? The levers are pulling as far tight as they can. There must be an internal adjustment between the lever shaft and the piston?

 

There may be an adjustment screw?
There may be an adjustment simular to a drum brake adjustment?
Or, tighten up the center cable adjustment and you might have to add a spacer, steel tubing, between the adjustment nut(s) and cable U-bracket?