Pfaff 1222E sewing machine repair

My beloved Pfaff 1222E sewing machine started to slow down every few stitches. I was able to hear the motor noise, when it had to choke through that position.

The Giraffe investigated the machine and found a crack in the Cam Stack Gear (calls in German <<Kurvenblock>>). The wider distance between the two tooth caused by the crack, was the cause of the problem.

Thankfully, a specialised sewing store was able to order a spear part, so I managed to replace the broken gear.
…Really, this is simply gorgeous! The machine is about 35 years old, still works AND YOU STILL CAN GET SPARE PARTS!
No words about what I’m thinking about machines from China…Nihao!

To slip out the gear block, you have to lift slightly the whole automatic mechanism module. To do this, you maybe have to remove the screw (16). During the re-assembly, carefully make sure the marked splints in the metal bars in the picture below found their correct positions.

Update:

The red marked 4 screws are holding the whole assembly down. After loosen them you have to sligtly lift the whole assembly. Then remove the  screw indicated by the green arrow, to remove the stoper thingy. The gear should slide from the shaft afterwards.
However, bringing all together is a little bit fiddly!!
In the sketch above the parts which should match up are highlighted.
You may want to use a torch to locate the marked metal rods under the assembly.