I bought a replacement speedo
I installed the speedo and went to try it out but it doesn't work. The light comes on but beyond that nothing.
Could you be a little more specific about the actual make/type/ID number/directon of cable rotation of the "replacement speedo" unit?
Also what ID number*/ratio*/cable rotation is the drive gearbox? *(you can find this information stamped on the rear of the drive unit)
Does the inner cable turn when the wheel is turned?
Are you sure that the upper end of inner cable is fully engaging with the drive spindle of the speedo?
Check that the direction of drive gearbox/cable rotation matches the speedo? You should be able to make the speedo work by "motoring" it using an electric/battery drill and a small rod with a squared-off end that will fit the recess in the drive spindle? You may need to set the drill on reverse to check this?