Repairing
A very brief description of how a Newlander in my opinion is built, take a large sheet of ply, next some 2X1" timber build the basic frame including the luton, fabricate out of chipboard the front and rear top curved panels, and cover the inside with a faced ply, using the same 2x1 make the cupboards seating/bed partition walls and again cover in ply, all the wiring is then installed behind the panels from the outside and the plumbing from the inside, the fibreglass and aluminium panels on the outside are then fixed using glue, and on the edges a beading over the places it is screwed, neat folds make a watertight joint where the panels meet. Of course in this process windows doors and fitting are put in. I know this is very simplified and there is a lot more work involved and basically its what I have found as I have took various things to bits to repair, So if you happen to know different or have actually been involved in the building please contact me.
Rusty screws and bolts, A few tips.
Screws, Spray with a good penetrating oil and leave for a couple of hours, using a good quality screwdriver or bit tighten it a tiny bit and then try and unscrew while pushing down hard, if this does not work and its a Philips if you have room to get a metal saw in then cut a slot and try with a flat blade driver, if this fails then drilling out is the only solution, using s small drill bit drill a pilot hole in the centre of the screw and then try and gently remove as much as the screw as possible the drill will want to take the easy route through the timber so you have to be really gentle and patient, of course if you have no need to use existing screw holes then you can just drill the head off.
Nuts and Bolts. It's well worth using penetrating oil at least a day before you intend to do the work, and to keep spraying it as often as you can, once again a good spanner or socket is well worth investing in, a long bar is also useful for extra leverage, getting some heat on it helps but is quite risky depending on where the nut is and finally if all else fails a nut splitter may be the only answer.
Damp.
If you manage to find a classic camper that has no damp then either its been restored or never used being kept in a heated garage, damp will always be a issue with classic campervans due to the very nature of what they are designed to do, as soon as you begin to cook in one, because of the lack of double glazing, condensation runs of the windows and wallboards, especially when it is cold outside, so over the years certain areas mostly out of sight Your pretty sure to find some damp.
The Newlander is basically like any coachbuilt the only difference is, its built more like a caravan then added to a chassis, hence why there is no access from the cab to the back except by leaving the cab and going through the side door, but the principles are the same for treating damp.