To get a better understanding of your issue I took a snapshot of the front suspension drawing from the parts manual for the Aero Plus 8.

[Linked Image]

Although the coil spring damper assembly, part 12, is drawn with little detail can I assume the damper spindle screws into a thread in the top bushed collar secured with a locknut? If so it seems likely the female thread in this collar has partially stripped. If so it's hardly surprising it's parted again. A lot of supposition here but if correct a new coil spring damper assembly would surely be needed.

Apologies if I've got this completely wrong.

Richard

2018 Roadster 3.7
1966 Land Rover S2a 88
2024 Royal Enfield Guerrilla 450
1945 Guzzi Airone