Hi Vaclover
1st question - I guess it behaves that way. When you choose the separate prewash (AKA rinse & hold cycle : A + second button from left) does the timer advance to the stop position by itself making a sort of "fast forward" (rapid advance)?
2nd - Havent' seen your DW, how can I say which exact model it is ? ;-)
If it were a white fascia one it would be a Favorit 525w ... if it were a built in machine it would be a F 525i
3rd - 65>>50 means : button released = 65°C , button engaged = 50°C.
Now I'm not @ home. When I' ll be back there, I' ll make some scans to the 1985/86 A.E.G. catalogue