I did contact Sachs, the response I got is below (I have not included the PDF but trust me there are 18 things listed on it!!!)
Thank you for your reply. we know that the VW Golf 150pd can be quite a problematic engine. There are various things on the engine side of things that can contribute to DMF Failure. These can be things such as -
· Worn cam lobe's on the cam shaft
· Detiorated wiring harness for the fuel injectors
· The tips of the injectors can get a carbon build up causing the spray pattern to change, which in turn will increase the amount of vibration the DMF has to damp out.
Please see the attached PDF bulletin.
The warranty period on the SACHS DMF is 24 months, unlimited mileage. This covers you only against genuine manufacturing or material defects on the product. If the flywheel has failed due to mechanical overload/ over stressing the DMF due to problems like the ones mentioned above then the part will not be covered under warranty.