My pedal is very stiff, I put it down to the modifications adapting from 2 bbl to 4 bbl that was done by a previous owner, I will fix as necessary.
I will be pulling cable out and checking as C.P. has said to make sure it is not binding, then a light machine oil down the cable and as light a spring as possible for a return spring. I like the idea that UKcuda put forward, will look into.