I have a leak from left-hand side of the machine
Water drips from the left-hand side of the machine when the machine is running, and maybe afterwards. But I can't see any obvious leak.
There are several possible causes of this. It helps to have a look at a parts diagram - see the attachment in the seventh post of this thread (that's for a G532 but the parts seem to be the same - I think it just has different wash programmes). The reference numbers given are those you can quote direct to Miele to order the parts (and they're still available in 2010).
The most basic it could be is the rubber door seal. This comes in two parts - a U-shaped section (number 130 on page 1) to go around the sides and top of the machine, and a straight section to go along the bottom (number 270 on page 12). The U-section just pushes in, while the straight section needs to be screwed to the bottom of the machine.
If the rubber looks in good order, it could be the spray arm sprinkler seen on page 6. The plastic nuts 30 and 60, and the rubber seal 20 become brittle after prolonged exposure to high temperatures and the threads disintegrate. If you get white dust on your hands from handling them when wet, this is probably happening. Replacements are about GBP13 each from Miele (GBP5 for the seal).
Alternatively it could be a leak in the feeder tube 10. This is heavily embedded in the blown polystyrene foam casing of the machine (and the metal outer casing is welded together, so you can't remove it).
First, order a replacement (about GBP90). Remove the machine so you have good access all the way around. Clear the polystyrene from the top so the feeder tube is exposed, and unscrew nuts 30 and 60 so the top end of the tube is loose.
Next, cut the bottom neck of the feeder tube with a hacksaw near collar 40, so it's a straight run upwards. Pull hard on the tube upwards to extract it (a bit of hot water may help here). Also remove the bottom cut end of the tube from the collar.
To replace, take the new tube and run some hot water inside to soften it slightly. Also coat the outside with washing up liquid to lubricate its passage through the foam. With luck it will press into place with a bit of force. Connect up the pipe at the bottom and screw in the spray arm screws, and test out the machine. With luck it won't leak!