Hi fellas, im working on my 2/300, i have need of some advice, not wanting to damage what i have. Dose the air/fuel valve unscrew from the tank? On this one it moves 1/4 of a turn anti clock wise. Is the pricker leaver removable, mine moves easily in both direction and moves in and out easily, for want of a better word its loose. How do i remove it to fit new seals etc. Ive attached a few picture. Any advice will be muchly appreciated. The valve stem dose turn with spanner anti clock wise but hits the centre spigot.