wrong answer --markysngc-
you first remove the centre plastic ecotec cover on top of engine
by sliding it to the right - underneath is a long black piece
(ignition coil pack) secured by 2 torx screws,remove these
there are 2 threaded holes also in the unit -if you have 2 screws that fit -this will allow you to pull up squarely on it
if not you can gently lever from both ends until it is free from the plug tops,
once you have removed it you then get a plug socket & extension bar to undo the spark plugs there are only 3 on this model. they are deeply set into the head,
check there is no foreign objects around the plugs first,
there shouldn't be but just to be sure,
if the plugs won't stay inside the socket allowing removal put some tape over the edge of the socket to make it a little tighter,
then gap & replace plugs & tighten to the
correct torque 25nm or18 ft lbs
then refit coil pack & screws & centre cover
you cannot mix up any leads
hope this is helpful
GSR600