From a 1973 set 8 manual. Model 8.7. Difficult to construct from the diagrams.
There were a few minor design changes to avoid bending a strip.
The main mechanism is as follows:
A horizontal strip with a long bolt on the end stops the drawer from opening. An arm from the drawer contacts with the bolt. When a coin (wheel disc) is dropped it moves the strip to a diagonal position which means the strip no longer contacts with the long bolt. As the drawer is opened the strip is forced to a steeper diagonal gradient causing the coin to drop into the cash box at the base. Once the drawer is closed we are back to square one.
There is a video of this model on YouTube, at time index 4:00.