Sounds like the friction material may be stuck and not disengaging or the linkage isn't working Ian
With the two large rear drive pulleys when the v belt is connected , one will always spin in the opposite direction to the other ,
hence forward and reverse is applied by locking one pulleys at a time to the shaft and neutral is when no pulleys are locked to
the shaft,the clutch friction material is used to lock one pulley at a time to the shaft.
Basic drawings below shows the patent for this drive setup so you can see how neutral,forward and reverse work.(copy and paste link)
https://www.outdoorking-forum.com.au/forum/ubbthreads.php/topics/78614/GREENFIELD_-_Theo_Reinhold_Pat.html#Post78614
Cheers
Max.
