Hi,

I've repaired two of these without running into the cracked gear problem. In both cases, the units were old and high mileage (180K and 270K). The repair mine needed was a simple reversal of the shaft that carries the odometer number wheels. Simple to say, not so simple to execute.

I would not have been able to test this at the junk yard, because the symptom was not a dead odometer, but one that would "lose" miles. Both would do this in the warmest part of the year, making it look like I suddenly cut my commute by half without saving any gas money.

Instead of a cracked plastic gear, the pot metal gear (clutch?) slipped on the shaft, wearing it thin. I don't know how anyone could check for this in the boneyard.

The one with 270K is keeping accurate mileage now at 360K.

For $25 you can buy a new gear. Be sure and count the teeth on your
cracked gear so you know which one to order. Replacement is a snap
once you get to where you can see the old one, which will undoubtedly have
a crack in it. The vendor (whose name I forget) advertises on this site.
--
George Downs Bartlesville, Heart of the USA!

Assuming it's a mechanical speedo, you can bring along a cordless drill. Chuck what I believe is a #1 square head bit into said drill (about $5 at Lowe's) and insert into the back of the unit where the cable would normally go. You can then spin the drill to check for proper operation.

We did this with a junkyard speedo, but after we got it home because I didn't have the tools with me at the yard. When we found the replacement to be defective, though, this saved us the time and aggravation of the removal/reinstall process until we managed to stumble upon a good one.

Greg