1995 b2500 318 4 speed auto. Speedo is showing 5 / 7 mph slow. I changed the 3 wire sender in the tailshaft. No improvement. Some mornings it will only show 20 mph for the first 5 to 10 miles. The odometer seems to be showing ok.
Any ideas?
Thank you.

 

Maybe pull the cluster, and go after the works for the speedo with some graphite lube... (dry lube of some description.)

 

The speedo is electric not cable driven.

Thank you for your reply.

 

It is told what to display by an electronic signal, yes, but, there is still a mechanical movement in there. Given the age, might be just a bit sticky.