You will find manuals (for example the manual for Adler Class 104 and 105 http://sew24.blogspot.com/2011/10/manual-for-adler-class-104-and-105.html), parts lists and other documents like sewing gauge overviews there which are not available in the regular download section of the Dürkopp Adler Homepage.
From the big number of downloads right from the beginning this seems to be very helpful for many people who are searching for these things since a long time.
Any suggestion what should be published there is highly appreciated in order to help people use and service their machines.
The first post about it was lost due to the virus. I hope this time it will remain.