I recently rebuilt my blaster and I am noticing it doesn't want to shift, if I shift without the clutch it shifts fine but for example if I pull in the clutch and start gearing down it will only go down 1 gear if I don't ease of the clutch a little it won't go down anymore at all even though I am still rolling. I have rebuilt many 2 stroke and 4 strokes and never had this problem. I have 10w40 in the transmission.