Do I remember correctly you can't use a alko braked hitch 3000 with a painted ball due to the paint fouling the coupling pads? Or have I made that up. Can't find anything about it. I've just got a new car and the tow ball is painted black
Before every trip out with the caravan I always wipe the ball with a scouring pad - nothing vigorous or course - just to make sure it's clean - even with a cap on the ball can get dirty or have slight deposits on its surface and this can cause squeaking noises on some vans.