i'm riding Kawa KR150, the gear sometimes just dont shift to 1st whether shifting from neutral or 2nd. I keep pressing the gear and finally it will get in first gear, and if luck, the gear from automatic jump out, if bad luck, it feels like the first gear wasn't 'shift enough', and it will jump out again.. I have no problem with shifting from N to 2nd, or any other of them.. can anyone help me with my problem? how much cost estimate for getting it fix?