We have lived full time in our Comanche for three years, and during that time we have replaced or fixed everything, literally!
The Autotrail cabinetry is better than most Brit vans but way inferior to the better German vans. We have found that our overhead lockers have sagged badly, with little load in some cases. Once they sag the doors start to bind on the other cabinetry, so a fix is needed. Nothing has been built with enough support nor screws, no strength anywhere, which ok for intermittent use when the sun occasionally shines in the UK, but not for the use we make of it n NZ, or full time.
The Comanche in particular has longer lockers which doesn’t help. But our shorter locker above the fixed bed is loaded with underwear and summer tee shirts, not a great deal of weight, and that sagged about 10mm, this I could see from a reference mark on the wall.
To repair it one has to get the warped cabinet raised into the correct position, not easy to achieve. Wilth the bedroom cabinet, first remove the one or two screws that hold the back of the lower cabinet to the wall. I was able to buy a long piece of stiff timber which I cut to the distance from the bed base (having removed the mattress) to the centre underside of the saggging cabinet. Then get a larger flat piece of wood, say a 12 mm piece of ply to fit between the cabinet and the long length of wood, this is to protect the cabinetry. Now jam the lot between the bed and the cabinet to force the long piece into the vertical, this forces the cabinetry back towards level. Tweak as necessary to get right. When satisfied drive a bunch of 25 mm screws into the lower cabinet back and into the vans plywood wall. I used a heavier gauge screw. Don’t over tighten as the wall ply is only about 3 mm, the the wall itself is about 40 mm.
The kitchen cupboard is a long story so briefly, it is poorly built, not strong enough for the microwave, not to mention our combination of melamine and chinaware. It is in two pieces with the join between the two cabinets, and hence sags there. Same technique as for the bedroom. Remove everything from the cupboard. Dismantle the shelves and bottom shelf. Remove the couple of tiny screws securing the back to the van wall, leave the screws going sideways into the surroundings furniture, but remove screws between the cabinets. Using the method described force the cabinet level. Add many screws into the van wall. But that is not enough. Briefly, I used very strong steel L shelf brackets to square up the four corners of the cabinetry, that is 8 brackets, yes heavy, but the only way to stop the cabinets becoming parallelograms rather than rectangles! Use long L brackets, as long as possible, drill more fixing holes thru the brackets as you will secure them with very short screws. Don’t use flimsy brackets, they must be totally rigid.
For the lounge overhead lockers, all I have done is add more screws into the van walls. They have sagged a little but due to their length there is no simple method of straightening them. I considered steel L beams, but the guage available and of suitable dimensions also sags over their distance, I experimented with that. Steel is not strong over distance.
Hope this helps someone, if you have a new van then I strongly recommend more fixing screws through the rear of your cabinetry into the plywood van lining.