There is odometer information on this board.

Google "brickboard 200 odometer".
Try different versions of the search if needed - you should get some results.
There's at least one source of the part(s) you will need, and good guidance too.

I never fixed one, though our "spare" '90 has a dead odometer.
I've read a few posts here, if I recall the problem is usually a tiny ring gear that breaks.

Replacing from a junker is only somewhat practical as there were changes in the speedometer/odometer every year or two around '89, and the sedan/wagon versions are not interchangable either. So boneyard pickings get very particular. Not to mention they could be broken too.

Most importantly -
IF you remove instrument cluster from dashboard, BEWARE the red and white wire in the dash. It is ONLY for a tach, but is present on all 240s. It will ruin any other componenet you hook it up to as it carries high voltage direct from the tach. So if you pull the cluster, tie up the red+white wire and put a note on it to prevent unintentional destruction of the cluster upon reinstallation.
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Sven: '89 245, IPD sways, electric rad. fan conversion, e-codes, 28+ mpg - auto tranny. 850 mi/week commute. '89 245 #2 (wifemobile). '90 244 (spare, runs).