Ah, you learn something every day, now I know those are a cable system.
I don't mean to be a harbinger of doom but the symptom's you describe sound very much like a failing release bearing, the only way of checking that is to pull the gearbox out.... In which case you may as well fit a complete clutch kit along with a release bearing and gearbox input shaft seal.
The bearing will be quiet while in use as there's pressure on it, until it totally craps it's pants them you'll get all sorts of noises combined with lack of a clutch.
That said I'm not at all familiar with the cable systems on those cars so do check that thoroughly as it could be something really simple.
