Now that your shrouds have been tightened, the mast cannot be turned on the step. Your rigger will have to loosen the rig to turn the mast. Before you do that though, take a tape measure and check the horizontal distance from the inside of each upper shroud to the edge of the mast step plate. On my Mk 111 , I found that the plate was not centered between the upper chainplates/shrouds. (Assembled on a Monday??)
To be centered in the rig, my mast has to be almost touching the starboard side of the step. (I now have a "spacer" block for the port side to remind me each Spring.)
With the shrouds, for-stay and back-stay loosened, the mast should then be able to be pried/pushed into the right spot.
Clare Jordan. Aragorn