Had a problem with my 78 4/4 recently 1st sometimes difficult to engage and always a crunch to engage reverse. Realised this had only occured since i had fitted new carpet which had decreased the pedal travel by the thickness of the carpet.Adjusted the pedal travel in the footwell by disconnecting the clevis pin on the pedal and increasing thelength of pedal travel with the locknut.Problem solved all nice and smooth! Hope this may help someone.
Barry