Going to Brands WSB earlier in the month, I was riding down the M1 and went to change down a gear when I realised the gear linkage had come apart

the main bolt which threads through the gear/foot leaver had come adrift, has anybody else had this problem
I have found myself that if If I tighten the bolt up to much it is hard to change gear but if left looser it drops off. Any ideas, cheers.
