The access for the fuel with Type 2 08/66-07/71 is locked through a flap door that is located at the right rear side of a bus. 

A spring clip keeps the door locked in 2 positions, but due to material fatigue or after disassembly it can get damaged. Therefore the flap door can’t no longer be locked and it can open when driving and will be damaged. 

From now on BBT can deliver a replacement each from stock.