I was riding home today on my 06 636 coming up to a stop light so im going about 35mph in 2nd gear pull in the clutch and downshift and i hear a loud grinding noise like something was breaking. So light turns green and i take off in 1st the bike is jerking real bad so i try to shift to second same thing so i'm crawling home at like 10mph and the chain comes off the rear sprocket i pulled over put it back on and made it home i was less than 1/2 mile from the house. Took the front sprocke cover off and the front sprocket looks fine the chain is on but wit so much slack you could take it off at either end. My question is what do yall think happend. I'm think some gears broke or maybe the transmission went bad. Also my bike is still under warranty would the gears and or transmission be covered? going to take it to the shop in the a.m.