More pictures and a video after the break
Underlying structure of the objective display
Underlying structure of the subjective display
The light leakages were solved using a combination of plaster and silicons. It looks messy but it works.
The original diffuser (±0,3 mm) was replaced by a super-thin matte tape (Scotch® Magic™ Tape). The diffusing effect is not as good as the original, but there are no more light leakages.
Video of the objective display where the current energy consumption is visualized.