I am having a random issue with shifting gears of my cultus 2006. When driving or idling I am unable to change gears (they become hard). Actually I notice that clutch stops working. If I stop the car and turn off engine, put the car in first gear, push clutch and turn the self the car gives jerk like in gear and clutch is not effective. Where could be the problem? clutch plate , pressure plate or gearbox?