I have searched for this but with no luck

Is there any info or "how to's" on how to adjust the gear linkage on my 1989 MK2 16V?
I have recently changed the selector ball, and all things are good on the gerr stick, but it seems that the linkage is out as I am having to really shove the stick left and up to get first, the normal action for first gives me third!
I has been sugested here that the fix for this is the linkage? is this true if so how do i do it, also any other things I should look for that may cause this problem.
thanks