Speedometer quit working

[JEB]

Hi,
The Speedometer on my recently restored M38A1 suddenly stopped working.
One minute fine, the next, well not so much.
I was driving to a show and going 40 or so, nothing unusual, but it was probably more stressed than it gets on my usual neighborhood ramblings.

Obviously, either the cable or gauge. Everything else works.s
The cable was checked and lived during the recent restoration.

I hope it is not the gauge since I paid semi-big bucks to have a new lens case installed on my original unit.

Anyone care to make a wild guess which it is?
Is there a weak point in the system?

If it is the unit itself, are there shops to fix it, I'd rather not buy a new repro since they don't seem to have the original
"8376375" and S.W. 503C markings.

If worse comes to worse, is there a shop to repair my unit or a source of a new unit with the correct markings?

Also, will the earlier SW 503A (Ord # 7760396) work?
My G-758 manual says they were superseded by the 503C and are for gauge clusters with different part numbers, I have no idea if that would fit.

I have also come across the SW 501C, but in checking I read they were for M151 and later trucks. Would they work?

 

[DeetFreek]

Must have been in the air, mine stopped as well! Disconnect it at the trans side and spin the cable, you'll need a spotter to see if it's activating the needle. As long as the cable isn't snapped, it should move. As for repair shops, I don't know of any. I'm not saying there are none, I just don't know of them.

 

[JEB]

Turned out to be a snapped cable.
At first, Dave thought the Speedometer seized and the cable twisted until it broke.
But when the unit was pulled, it was fine. So perhaps the cable was bound by something, perhaps the firewall.

So now I have a nice NOS unit as a spare.
Not actively looking to sell it but if anyone needs one....