I just did it. I managed to talk Palo Alto Speedo (www.paspeedo.com)into sending me a new gear on the advice of a rennlister. I don't know if they will keep doing that if flooded with calls.
If your gear is yellow (amber) and brittle, it is toast. Don't put a spacer in it is supposed to be loose like that. The idea is that if the motor or something else seizes the gear spits itself to the side to save the rest of the works. I was amazed that the new gear was almost rubbery and translucent white. Probably ABS or PVC or some other wax loaded plastic.
As far as the needle removal you need only move it off of the 0 MPH stop and lift straight up. It feels like you are gonna break it but it comes right off. Line it up with the zero mark and push it back on. That simple.
Watch out when putting it back together. I kept hitting the stupid thing with my finger when reinstalling in the cluster. Then you have to go through the needle calib. all over again. Works perfect now.
Ahh - Got it now. No I didn't have to remove the needle thankfully.
undid the screws at the back and the speedometer just comes right out
easily. Super! Yes I can see the gear - a 2-cog affair. That
is half chewed. I think the problem is way too much play back and forth on
the shaft. Without the play the gear would fully meeting the mating gear
and probably not chew up. I'm thinking that I can add something to fill
space on the inside and keep the gear pushed out and squarely on top of the
mating gear (maybe I can get a few thousand more miles??). I think I'll
that. Getting the pod and all off is pretty easy.
Time to go to get some replacement bulbs....
What I learned from a speedo expert is:
Don't use the special "mini prybar" that vendors sometimes supply with their gauge face kits. He's seen dozens of broken speedo needle pins due to (improper?) use of this so-called special tool. His technique is to use thumb and forefinger to gently twist the needle counter-clockwise and pull the needle up to disengage.
Put needle on the pin with slight pressure. Turn counter-clockwise to set desired "zero" position. (BTW, take note of this position BEFORE initial removal of the needle!) Tap very gently to set needle in place.
So the key here is that the little "pin" that the needle rests on is not extremely sturdy and if it breaks, well, you're buying a new speedo!
I have the same problem with my `79. It is a broken plastic gear. I found a place that will sell you that gear but they want $32.50 + $5.50 shipping for the gear. It is: www.speedometerplus.com
`79 928 5-speed
The place that I went to put in the brass gear, repaired and adjusted another
gear that was slipping on it's shaft, and checked everything for $75. That was
done by: Speedometer & Clock Company 2337 S.
Michigan Ave. Chicago, IL 60616 (312) 842-6378 Brass replacement gears are available from there, or complete speedometers can be shipped to them for repair.