English is not my native tongue and I so bear with me:
As I don't know what you have in front of you, I'll do my "I assume nothing" approach combined with my terrible drawing skills:
The items and function:
The bonnet prob (BKD360030) is the bar that hinges from the bonnet and that is secured at the hinge point with a clip (4B8769 - Clevis pin for bonnet safety catch hook). It can be cllipped onto the bonnet via a clip (CZH209 Clip for retaining/parking bonnet prop) when closing the bonnet
The outer end of the prob slides into a slot on a bracket at the innerwing: (14A7806 Bonnet prop bracket) As the end is in an S-shape (or should be) it can not fall through the slot of the Bonnet prop bracket:

Insert the bonnet prop in the the slot at position A and slide it to position B. the shoulder on the bonnet prop will rest on B now. It should not slide towars A on its own.
If the shoulder is not horizontal you shouyld rebend it in a vice (taking of the bonnet prop from the bonnet first)
Does the above help or can you determine what problem you now have?
Regards,
Johnmar
4B8769
Clevis pin for bonnet safety catch hook