I guess you missed some of the classes (Cluster Repair 101) when the instructors were describing the inner workings of the W123 Cluster.

Here is a Diesel Giant how to on removing the W123 Instrument Cluster.
How to Repair Your Broken Odometer


The clear face plate can be removed, but you will probably crack and break it. It is glued on pretty good.

I find removing the 10mm bolt at the transmission end, and pulling out the Spedo cable, then reaching down below the Brake Booster where it comes up and goes through the Fire Wall will give me a bit more slack when pushing out the Cluster from the back/under dash.

I find if I don`t, then it is tight to get my hand behind the cluster to unscrew the cable from the Spedo head.
There is also the big plug with about 15 pins that is in pretty tight.
Be gentle with it when wiggling it off. have read of some breaking the plastic plug.

Use a 13mm and a 10mm open end to remove the Oil Line.

DO NOT START THE ENGINE WITH THIS LINE REMOVED

You will get an oil bath.


This is not a difficult job.


Charlie

__________________
there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works