My gear lever decided to go all "mr floppy" last night. It rotates although with extreme difficulty i can just about find all the gears. I had a look at it this morning, and at the bottom of the lever, there is a semi circle ball in a housing. The ball has a slot in the side, in the housing, there is a hole...it looks like this is for a bolt or something to keep the slot in line and stop the "floppy" thing happening.
What is it that goes in the hole (if anything).....at the bottom of the slot is a grub screw of some kind, has that anything to do with it? Thanks for any replies.

yes grub screw with a spigot on the end

Spigot??

bolt with the threads ground off end to fit nicely in slot ,

Cheers, i,ll get to work in the morning.