How to disassemble it to fix the start button, which fell into the machine

Just adding to dhelkamp's instructions (which helped me immensely!).

The front quantity knob kan be pulled right out - it's held in place by friction only.

The side knob has 3 latches holding it in place. Releasing 2 is sufficient. Use 2 small flat screwdrivers.

As for the assembly, there are 4 latches in the inner assembly holding it in place. The location of these latches can be seen by looking at the edge of the outer shell. The front latches are just behind the holes for the rubber feet, and the rear latches are just in front of the rear holes. Use a flat screwdriver to release one of the front latches, while pressing down on the outer shell - it should give way 1-2 mm. Repeat on each of the other 3 latches, whilst keeping pressure on the outer shell. The cover should easily slide off the grinder assembly. Beware of getting pinched!

Given the sophistication of the German engineering behind this product I suspect that the manufacturing in China is not the problem with the switch failure due to material 'fatigue'. This is one of those pesky built in 'fail' designs that causes most consumers to simply go and purchase a replacement grinder.  The plastic tab which is an extension of the switch housing and (secured by a philips screw) fails through plastic fatigue and breaks free of the mount.  It is the most employed 'moving' part in this appliance and could have been much better designed for the consumer.  The design employed suits the stockholder's short term interest. Consumer frustration is well founded.  Conspiracy is just another word for planning!

Remove knob on side (carefully), pry seam on bottom edge of appliance (on underside) using small screw driver at three spots, one on each side, one in rear. Push on clear housing as you do this and entire inner assembly will slide out the bottom, allowing you to remove the black outer cover.

Ya know, the easy thing is to take it apart, then cut the two power cord wires from the timer/interlocks, then cut the timer/interlock wires going to the motor and just wire the motor direct to the power cords. When you plug it in, it runs, when you unplug it, it stops. Just measure your coffee instead of messing with the machine. You can still adjust the grind, which is the important part, and you have a pretty foolproof grinder (unless you are a fool!).

Be careful when you remove the 'shell' - the sping and the plastic pin that triggers the lid safety switch may be floating around in the machine. In my case, one of the screws of that switch losened itself - all I had to do was retighten and reposition.

Thanks for your posts!

I just finished fixing mine thanks to the above helpful solutions. I accidentaly broke off two of the three little latches that hold the side knob on. It seems to stay in place still. However I almost lost the little spring and white plastic cap from under the side knob. Luckily I can still enjoy the delightful click-click when adjusting the grind.

I used part of a heavy plastic laundry detergent lid to replace the broken plastic that used to hold the button ib place.

Thanks to wirving and dhelmkamp. Had the same situation where the starter button broke into the body. We successfully wired the power directly to the motor. Working like a charm now.