Don't think so as I've had mine apart a few times.
I did notice that the door hinges on my van have 2 pivot points, perhaps if one is sticky the door isn't fully in the opening..difficult to explain but worthwhile looking at.
No. Years ago they had problems and were replaced foc but not like your issue. Has the gap shrunk ?
Easiest thing is just file off the edge of the lock until it releases. It still locks and I assume will have enough material to stay secure?
I vaguely remember having a problem with a Hartnal lock on a previous caravan. Can’t categorically remember if it is what you describe but have to say it sounds familiar. Whatever it was, we squirted a load of lock lubricant in and it was sorted. Like DD I remember that Hartnall locks were well reported as troublesome in the past.
I suspect if this is a new issue then the cause is likely to be wear on the cam surface of the shaft or the matching faces of the latch tenon plate that forms the latch.
I can't recall any designed in provision to counter this; it is a rudimentary moulded plastic affair, I suspect in ABS.
Build the worn cam face up with a bit of Aradite or "weld" on some ABS scrap using pipe solvent might be viable solutions. This will need dressing up with a file etc but not an overly challenging task to an enthusiastic DIYer.
Though I would take the easier route and simply carefully take a bit off the latch as suggested above.
Edit: THIS link gives some hints of what one will find inside generic Hartnal locks.
I had exactly this issue this week - it can only have been a thermal expansion issue as it only happened on the hottest day of the heatwave and subsequently fixed itself. Using the external handle meant it didn’t quite clear the latch but using the internal handle was OK. It took a bit of tugging but opened with a bit of a clunk. I came to this thread looking to see if a solution had been offered.
Hi, it was deff a heat issue and now the temp is back to mortal temp it is opening with no catching at all, it was the same thing that happens with UPVC windows and doors so thanks peeps and it’s back to normal now, we are 4 days into our 3 week holiday and we are not sorry that the burning temperature has abated.