Great description of how to replace dash lighting. I just did mine again (third time in the 25 years I've owned my 968) and would like to add a couple updates.
First, I replaced the bulbs with LED, Sylvania 194 LED specifically. Perfect fit and dims with dimmer knob. Way brighter than the incandescents.
Second, there is an inexpensive flexible mirror sheet product I bought, cut out pieces to fit the mirrored sections of the dash assembly, and used a bit of spray adhesive to fasten in place. Worked great! Here is a description: Fantasyon 10 Pieces Flexible Mirror Sheets.
One more thing: be sure to disconnect the car battery before you remove the instrument cluster. Otherwise you might accidentally ground the flexible circuit board on back of cluster and burn it. This happened to me first time I removed mine years ago, it actually burned through some of the printed wires. Had to repair with a circuit pen.