I'm in the process of repairing my odometer.
it all started by first noticing the odometer didn't move, but the speedometer worked okay (although shakey). i took it apart and noticed the 2nd worm gear (plastic) was stripped, but why?
If I turn the speedometer cable housing it still turns the plastic gear, so the 1st worm gear on the magnet seems in adequate condition.
I also noticed that if I manually turn the 3rd worm gear (metal) with some needle nose pliers it would bind with the gear with the numbers.

I would think this should turn relatively freely. I'm thinking this caused the 2nd plastic worm gear to strip.
I took out the 2nd plastic worm gear, and tried to turn the numbers again, thinking their shouldn't be anything binding, but it still got stuck.
then I removed the 3rd metal worm gear that meshes with the odometer numbers gear, but i still couldn't get the odometer numbers to turn when trying to turn it with some needle nose pliers.

Has anyone seen this before?
Am I missing something?





Stripped 2nd worm gear


Removed the 3rd worm gear that turns the odometer numbers, but i still couldnt turn the numbers gear

Should the plate that the "teeth" rest on have these cut outs?



I reinstalled the numbers shaft with the "teeth" not in their groove, but it still binded up once it turned

If I remove the numbers and just hold the teeth the same way they are held in the speedometer, I can't turn the gear

Cant turn the gear on the right

Is there a way to repair the numbers gear?

 

I wasn't sure if odometer numbers could be disassembled and reassembled without destroying it.
But I was pretty sure the odometers numbers were junk in their present state, so I took the risk with the hope to save the $50+ dollars to replace it. Also, I couldn't really find any replacements that are exactly the same as the C3. I saw a few vendors had C2 odometer numbers that look almost the same, but have a white number roller for the XXXXX digit.
Turns out you can carefully remove the little pressed on washers and remove the little parts.

 

Its been a few years since I had mine repaired. Same problem as you describe. If my memory serves me I believe it was a worn sleeve bushing that causes just enough slop and the gears don't mesh correctly. The binding causes the stripped gears. I sent mine to this company and they did a correct repair and my odometer works perfectly.
https://www.redlineg.com/
Norm
BTW this is somewhat common with the early C3s.

 

After removing the pressed on washers, you can remove the little parts.
thats where I saw the problem; the shaft was corroded in one part,, freezing up at least one of the rollers. I removed all the rollers and parts and did some gentle buffing with some steel wool. You could also use some high grit sand paper and use steel wool after.

Notice that little discoloration where the corrosion happened

 

Here are some more pics of the parts



notice the little orange gear has the side with half cut gears on the side of the previous roller

Polished shaft. Im not totally sure why they would put a copper plate on this. Both metals corode, obviously, but you can see it scrubbed of here

 

Polishing the shaft reduces the diameter, so the pressed on washers were loose after. After reassembling I put some super glue on the end. Hopefully this will hold it.

lots of folks talk about just replacing the plastic gear with the metal ones available, but don't address why they get stripped, and this is the first time I've heard of anyone dealing with the odometer numbers being the issue that caused the stripping, so maybe this will help someone down the line.

I wish vendors sold the plastic 2nd worm gears as replacements, but all I saw were the metal ones. If there is ever an issue again, it will likely cause much more damage, on the first worm gear, one of the issues Willcox calls out.
Mine is stripped, so I had no choice but to order the metal one.