Good idea! I've started it as well in earlier times and never ever use it.
But it's much easier:
- salmon relays should always get replaced every 5-8 years to avoid troubles
- micro switch coupling lock should always get replaced every 8-10 years
- battery should always get replaced every 6-10 years
- the 2 hall sensors on the right coupling lock should be checked for cracked and/or rusty plastic housings
broken wires in the rear roof shell. Should be repaired on both sides for all 3x2 wires to avoid repeating issues with broken wires.
Leaving 20% for broken hydraulic hoses in the rear roof shell.
The rest is based on water in the trunc (should always be checked at first) as well as violence against the roof package or the trunc lid by the Z4 owners (caused by one of the above listed, missed tasks).
Unfortunately, diagnosing/working based on fault codes doesn't lead to success in every case, as sometimes no fault codes will be stored, in other cases WRONG fault codes get stored.
We should set up a half yearly repair happening to train you guys on the roof.