Speedo fixing (Jaeger)

["James Carruthers" <j.carruthers@rave.ac.uk>]

My speedo seems to get stuck at speed - it'll go up to 50 and stay there - them 
it'll fall down to about 30 - i imagine that some sort of return spring has 
worn out - thus stop it from going down to 0.
 
I've taken the dial out - and if i lift the needle by hand it sticks. 
 
Any suggestions? 
 
J