Thanks Pete, 
I did just what you suggested: I undid the four screws and rotated the cover around the speed lever - job done.  Thanks again.
I have a few more questions now, though.......
I changed all the oils as per the manual.  Messy business!  Nowhere in my manual does it mention the sight glass for the headstock oil level behind the rear shear.  I only found it after I had the top cover off, by dipping the oil level to the rear of the cavity.  The gearbox oil change was fine.  But the apron....there is a filler plug and a sight glass, which was empty.  When I unscrewed it a trickle of fairly dirty oil came out.  I flushed the apron with thin oil and then refilled with ISO 68 - most of which ran out of the rear of the apron, leaving the sight glass once more empty! Am I missing a plug somewhere?
The High Speed - Low Speed change lever is temperamental - sometimes it moves smoothly and others is is a pig to shift. I know it has to align with two sets of gear teeth, but is this normal?
Many thanks again for any answers, 
John