Z1OwnersClub GB

I am giving My carbs and overhaul and have noticed that the metal shim between the two throttle stop adjusters on cyllenders 3&4 is broken. This shim appears to be made of some sort of spring steel what is its purpose and in its broken state will it make a major difference to setting the carbs up? i.e, balancing. Please see attached photo as my description of the item is probably not what it is really called, all opinoins welcome!
P,S Is it possible to purchase a new shim or could I make a new one from an old coke can

Available from z power which are slightly thicker than the originals

Than's Paulstrees just checked on the Z-Power website part no 16054-005
£3.00 each. I will se if they are at utoxeter tomorrow if not ring on monday