tried setting the mixtures on my s1 (mfi) but the adjustment screw is not the proper one..it has a small bolt instead of the allen type (i think thats correct?)..the car runs but is quite lean..co level only 1.6% instead of 3% so ive been told..what im wanting to know is can i put a longer bolt in it as i think the screw needs turning more clockwise to increase co level..also what other things have you done to replace seized mixture screws..cant seem to get hold of a good second hand 1 with allen screw intact and not seized..thanks