Beogram 6000 (5512): Repair of a Wavy RPM Trimmer Scale Background

After replacing the background illumination bulbs in the RPM trimmer panel with LEDs I realized that the white  reflective background that homogenizes the illumination was wavy causing a 'zebra pattern' in the illumination:

This seems to be an issue that only affects a subset of Beogram 400x. I only had to do this once before so far. To fix it one has to take the panel assembly apart. This shows the panel from the back:

The white part needs to be separated from the aluminum panel. This can only be done by cutting the locking washers loose with a wire cutter:

Then the parts can be separated:

This shows one of the wavy white stickers close-up:

The wavy pattern causes a variation in the reflection of the light piped in from the previously installed LEDs. The original white stickers can simply be pulled up with pliers (one needs to be careful to not break the red dial hand off). Once removed it can be replaced by white electrical tape cut to size:

The panel can be reassembled by using new 3 mm circlips and nylon washers:

After this procedure the background illumination was smooth again:

Beotiful! On to replacing the badly corroded DIN5 plug...