We have sidewinder on our Rockwood 8280. You have to get the angle absolutely spot on so that kingpin and wedge engage in hitch properly. Only time I’ve had real problem was when the wedge was wrong height and locked in the jaw took a number of attempts rolling forward and back before position was right and handle could be disengaged. If you are having to persuade with a hammer then wedge is probably the problem. If you haven’t already bought the hitch on eBay I’d try fixing the sidewinder and removing the wedge. Rig will then rotate over the truck rather than at the van end. Might also make reversing on easier as kingpin arm will always be straight rather than at whatever slight angle your last reversing manoeuvre left it at.