This just happened to my Braun 3612 shaver, too. No diagram - sorry - but here's how I fixed it (you'll need tweezers or a toothpick):
1. Take off the top part that holds the foil. Hold it in one hand with the open end up - the trimmer will fall downward because of gravity, but you should push the trimmer back in and hold it that way.
2. Take the "small part" in your other hand and position it so that the long, needle-like bit points down, away from you. The top of the "small part" has two flat arms, the left arm being lower and a little longer than the right. It should look sort of like this: ___,,--
If you look at the base of the trimmer within the foil housing, the left-hand part follows a similar shape: ____,--------
3. Insert the "small part" (needle part first) into the slot just above that bend in the trimmer base. This is the only way it will fit. The right arm of the "small part" has a tiny knob at the end. You'll need the tweezers or toothpick to push that knob down so that it locks into place.
4. If you've done this correctly, you can let the trimmer drop and the "small part" will stay in place, tilting with the movement of the trimmer. Put the top back on the razor and the trimmer should work normally again.
Hope that helps!
TFY, December 2007
