If the greenhouse is in a ‘flat pack’ pile of cross members and pieces of aluminum, it is more difficult to work out if the whole thing is actually there, and which bits go with which.
Moving and dismantling
Do not attempt to move a greenhouse any real distance. The aluminum design greenhouse is really good at withstanding torsion when there is glass in it but even the forces exerted in turning a corner can twist the frame, and if that happens it is useless.
Before you take the greenhouse apart, check it for squareness. This shows itself in two ways. Usually when a pane breaks it smashes altogether and needs replacing. Cracked panes are a ‘tell-tale’ sign of the greenhouse being out of square. You will also see gaps between the glass and the frame.
The next thing to worry about, if you see the frame is not square, is the cross members might be twisted, so have a good check all round. A plumb line will show you the direction of the lean and if you gently push in the opposite direction it should easily go straight.
If you hit the spars with a screwdriver they should have a muffled ring. If they thud or buzz there is a problem to be investigated.
When you dismantle, mark the corners and joins with different coloured nail varnish or paint – then you know which bits join without having to make complex diagrams.
Remove all the panes of glass and clean them before putting them between newspaper. Store the glass on an edge and do not put more than five panes together. The glass is held in position by two clips. A spring that locks the glass against the frame and another that allows the top pane to rest on the lower one. Always wear gloves when handling glass.
When the nuts are removed from the frame always screw them back onto the bolt because they corrode in place and are almost impossible to get onto another. If you remember, take a tin of oil with you to pop them in.
The roof and side-walls have rubber seals that act as a cushion between the window and frame. These perish and crack and become useless. Some garden centres do stock rubber seal but you might find it impossible to find replacements. You can use anti hot spot tape, either cut long-ways (very fiddly)
It's always worth buying new glass clips for the panes