Ok, well my advice would be to go to your Maintenance outfit and ask to borrow their compass. If they are any good they will say "sure". You then swing the aeroplane, and write down your results. Then go back to the engineer and say "here, can I ask your advice" and ask him to adjust your screws for you, or you adjust them under his (her) supervision. Bung him 20 quid or a bottle of scotch for his trouble and then you are done legally.