Two  different  levels  are  in  Gearbox.
One  beside  gearhandle  should  be  easy  enough  to read
Second  is  accesible on  plate  on  right  hand  side   I  think  that a  23mm  spanner takes  it  off right  beside  where  the  clutch  adjustment  is
                
 John O  Donnell
                
 February 2009