Cluster light confusion (post-dimmer-repair)

[bnoonan]

OK. I know, the dimmer.
My interior lights (cluster & AC buttons/sunroof button etc.) have not worked (flashed on once) in the 4 months I've owned this '80 300D.
Got the LEDs from mercsource (n=3) and pulled the cluster today. Had to fix the odometer too.
Fixed the odo, pulled the dimmer (it was good, just a fair bit of corrosion on the center circle) and cleaned it up. Put it all back in.
(NOTE: don't let clock power wire drop down and hit the key cylinder...or you will need a new fuse; ALSO NOTE: make sure your speedo needle is above the bottom pin before you reinstall, or you will peg out at 1mph).

Post-repair, odometer works. Lights for AC and Sunroof work (and dim). The cluster still does not light up.

In replacing the cluster lights with LED, I replaced the top two, and then another on the bottom right that was also large. Not sure what that is for or if I should have, but figured it wouldnt hurt since I had 3 LED bulbs. But my understanding is that it is the top 2 bulbs I'm interested in for illuminating my speedo/etc. (note: all other bulbs down there work fine [battery, glow plugs, etc]).
I know the LED bulbs are 'sided', so I tested them with wires and a spare battery to make sure they work (had to flip 2 around to get em to work).

So, I thought the dimmer was my problem..and it appears it was, at least in part. But why, if the AC lights now work, is my cluster still dark. Any ideas?

Thanks,
Brice

[bnoonan]

Any ideas?

[BWhitmore]

Your cluster probably needs a new ground. Attach a new brown ground wire to the back of your cluster (there are several places to attach a ground wire with an existing screw). Connect the other end of your new ground wire to the steering column drop bracket where the other brown wires are attached. This is a common problem with the W123 cluster lights.