I have a 6 speed so relevent to that box. Unsure if the 5 speed is the same on the NC.
If so do check you have oil in the turret, they can dry out. If you have oil in there it can be syringed out and replaced. It doesn’t take much, an egg cup full is about it.
I’ll try and find a pic and link👍
Here you go, my memory not so good, in this link it mentions the 5 speed having turret oil.