Our tumble dryer had recently developed a similar leak dripping water on the floor around the rear left side of the machine. I stripped the machine down, cleaned everything in the process and ran the machine with the sides off to investigate.
In my case the problem was that water would drip over the edge of the condenser tunnel (especially when the fan blows hard) and drip on the floor. I checked that the condenser was fitted correctly (it was) and ensured the machine was level (adjust feet if not) but water was still blown over the edge of the tunnel where the cutaway exists to allow the airflow to pass through the condenser and exit the machine.
You can see the water dripping over the edge in this picture.
I then checked that the water pump runs continuously and was pumping the water into the drawer without any blockages (which it was) and then fully cleaned the water pump assembly anyway and all parts of this machine are now as new.
The problem was simply the front and rear rubber seals on the condenser unit had worn out and needed replacement. You can still order these direct from Miele and cost around £29 each. The condenser tunnel should remain completely dry during operation and with worn seals the water, at the back especially where it generally collects prior to being pumped out, can leak back into the tunnel and be blown over the edge as described.
You can buy a complete condenser unit assembly for around £260 online but you only need the front and rear seals assuming your original is intact, which it should be unless you've dropped something heavy on it.
The Miele parts catalogue can be accessed here (Miele parts catalogue) and simply enter your model number.
The catalogue also shows a piece of sound deadening (No 6) that fits over the cut out in the condenser tunnel and this was missing from my machine. However, this is no longer available from Miele and frankly unnecessary anyway as it must surely restrict the airflow out from the tunnel? As mentioned the condenser tunnel should remain completely dry during operation if the rubber seals are working correctly so the sound deadening should never get wet. My seals (No 13 and 14) didn't look in too bad shape and were still flexible but new ones have fixed the problem.
Miele appliances are so well built and each individual part or unit in this tumble dryer is perfectly designed and simply join together with the other assemblies to make the whole machine. Simply cleaning them will make the appliance look like new. There were no nasty sharp edges anywhere on the appliance and it has gone back together perfectly. The comparison in build quality compared to much cheaper appliances is noticeable, these machines really are built to last.
If you've already taken the back metal plate off to investigate (No 24) you'll need to remove all remnants of the old seal completely and refit using RTV available from any good car parts store. RTV is used on cars to seal oil sumps, head gaskets and similar and generally works to temperatures over 200 degrees celsius. The back of the machine naturally gets very hot during operation so RTV or similar is required instead of silicone sealant.
Hope this helps anyone that has a similar problem.
29 
23 
17 
