Hi All,
First time poster here.
Got my W123 a few months ago and have been doing a number of repairs.
Worked on the instrument cluster on the weekend,and managed to fix the speedo (lubed the cable) and the dimmer -so now I have instrument lights and a speedo that works below 60.Thanks forum members!
My problem is,that when I go to put the cluster back in,the thing just won't go all the way in.
Protrudes about 2-3mm at the top.
I've tried lubing the rubber gasket and dash surround,but it's just too tight!
I've pushed so hard I almost broke the perspex cover.
Alot of people have posted about removing the cluster and putting it back with no problem.
I'm totally stumped.
Any help would be appreciated

Check the clamp for the speedo cable on the firewall.

I wouldn't worry about the speedo. Most of the time those nice uniformed guys will give you a piece of paper telling you exactly how fast you were going!

__________________
“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now

Thanks for the response
What do I need to check for?.. I did try pulling gently on the speedo cable from under the dash to make sure the cable wasn't pushing back.
It doesn't seem anything is pushing back -seems more like the size of the space the cluster goes into has shrunken -there is so much pressure on the edges of the cluster at the top front, when I try and push it in that I can see the perspex cover wants to break off around the top edge

If I remember correctly, tilt the top of the cluster towards you and insert the bottom of the cluster in first. I seem to remember the rheostat tends to bind on the bottom of the opening and hitches the whole assembly up.

I usually remove the retaining clip on the speedo cable and reinstall it after the cluster is seated.

__________________
“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now

I agree with this. It comes out mostly straight, but best to go in bottom first.

Op also be careful with the little bulb holders on the bottom edge when getting the cluster in. They protrude backwards and will permanently dent the dash near the key tumbler. Ask me how I know...

__________________
Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (113k)
1991 350SD (206k)
1991 300D (228k)
1993 300SD (291k)
1993 300D 2.5T (338k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (265k)

Past Diesels:
1983 300D (228K)
1985 300D (233K)

The speedo cable holder is located on the driver's side junction of the back of the engine and front of the transmission. It is not unusual for the top of the instrument cluster to protude from the dash about 1/4 inch. On all three of my 123 cars, they all protrude by 1/4 inch.