Speedometer sticking at 42mph?!

[spikevyxel]

Basically, during random parts of any trip i take in my 5 speed 95' KA 240 my speedomter will stick at about 42mph even if i'm going that speed. It returns to normal once i make a stop and once i start accelerating again it raises from 0 to 42mph exponentially.... it accelerates with the speed, only that when i'm at 5 MPH it says like 25.. then it just stays up at 42. This happens at least 4-5 times during a trip and goes back to normal just as fast as it sticks.

i'm at a total loss.

correct me if i'm wrong, but the speed sensor is on the tranny and this problem started happening at about the same time my synchros started hardcore giving out.

any sugestions would be greatly appreciated...