Replacing Suzuki B105P Clutch Cable

[robster94gt]

Hey all,
I've been working on an old Suzuki B105P, and am trying to replace the clutch cable.

I've got a Haynes manual for slightly later models of the B100, and it shows the cable end is easily accessible when you take of the right side cover. However, on my bike, the setup is different and you can't see the mechanism. It seems to be inside. There's small nut recessed in a white plastic piece, but I don't want to mess around, until I'm sure of what I'm doing. I'm getting the feeling that I might have to open the gearbox to get at it? I hope not.

Thanks for your help,
Rob