5mt shift linkage problem

[Canadian818]

Can anyone tell me what the part in the picture is called? One end of the shifter locks in it and the other end engages 1-2,3-4,5-R. For some reason it won’t let me twist clockwise (from the back) to select 5-R.

[Canadian818]

So I guess it’s called the Reverse Check Sleeve. Now to figure out what’s wrong with it.