well back from my play
discovered one of the screws is horribly bent which won't be helping
unfortunately during the mucking around i have completely stripped bare one of the other screws
and it doesn't seem to want to come out! i did not want to use much force
the good news though is despite the carnage i have the laser dot bang in the center now, with a combination of doing a slight adjustment to the entire secondary position itself plus the 2 other screws. probably a huge fluke but it'll suffice until I work out how to fix the bent screw and the stripped screw.