It's easier than that.

Speedo can be removed without disconnecting the oil pressure line -- drop the parking brake bracket, reach up and unscrew the speedo cable and the white plastic knob that retains the instrument cluster. Pull cluster out, reach around behind the speedo and remove the three phillips screws that hold it in and use a pair of needle nosed pliers to unclip the wire retainer for the cluster lamp. Gently remove speedo from cluster. You can pull the dash dimmer at the same time. Knobs for odo reset and dimmer stay on the cluster.

Once you get the speedo out, the fix is very easy. Get some locktite, low set (blue) is better, but either will work (red or blue). Push the shaft that goes through the milage nuber wheels all the way toward the metal drive gear (passenger side of speedo) and push the metal gear the other way for clearance.

Whittle down a matchstick or use a broomstraw and use the tip to tease a small drop of locktite down onto the shaft. Work the shaft back and forth to get some between the shaft and the gear, then use some paper strips to get all the excess out. Wipe the end of the shaft that goes through the sheetmetal flange clean, too. Adjust gear and shaft to original position -- if you leave the gear pushed over tight against the number wheels, they can all turn at once!

DO NOT get any locktite on the plastic gears or number wheels!!!! ONLY between the zinc gear on the outside and the shaft.

In a couple minutes, the locktite will set up and the odometer will work. Test by putting a tapered matchstick or similar in the speedo cable fitting and spinning it. Hole is square, whittle to fit. Spin to give positive speedo needle movement, otherwise the odo counts down....

I'd use a bit of rubbing alcohol to clean the number wheels, especially the tenths wheel on the trip odo while I was in there.

Installation of the now working speedo unit is the reverse. Takes about an hour if all goes well, longer if you drop the cluster bulb and have to fish for it.

If I ever get around to it, I have a spare speedo I will use for a DIY article.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!