agree with my fellow frenz...
1st. change gear oil. if too dirty, there might be residue, so flush it. if u think putting additives will help, dont hesitate to spend.
2nd. check clutch cable adjustments. if kenot adjsut summore, this is early sign clutch worn. or maybe clutch bakar. after driving, try to detect for any burnt smell at the lucth housing.
3rd. for clutch actuated by hydraulics, i afraid maybe the pump inner rubber worn out and expanded thus kenot apply pressure effectively. change repair kit and bleed. bear in mind there are two pumps involve..master pump and slave pump.
these are all the things u shud look before u start dismantling ur gearbox. i agree with speedking, during idle try masuk gear 3 and without releasing clutch, masuk gear satu. do this test a couple of times and then try with 2nd gear oso. then try to change hear normally from 1st to 2nd. if still not ok, sumthing is not rite there inside. good luck to u!