Clutch hydraulic issues are seen quite often here; LHD cars use a cable clutch and don't suffer from this. RHD models have a hydraulic system which, let's just say, looks like it was a bit of an afterthought. There's not much fluid in the system, and what there is tends to weep from seals, etc; the parts aren't exactly cheap, either. I'd highly recommend preventitive maintenance in the form of changing the clutch fluid every two years (at the same time as the brake fluid); it's subject to exactly the same degradation.
Usually the first sign that all is not well is a slight difficulty in changing or engaging gears; it's important to get this checked out as soon as possible, as driving in this condition will lead to rapid wear of the synchro rings inside the gearbox.
If you're buying a secondhand RHD 500, lie down and look up into the driver's side footwell for signs of hydraulic fluid leakage; you can see the end of the clutch master cylinder and any seepage should be readily apparent, normally just where the actuating pushrod comes out of the cylinder. This picture shows you what to look for.