So i got a pretty good deal on traded my atv for it iy 5500 miles when i got it i was told 2 gear doesent work witch it doesnt. the bike run perfect and drive flawless as long you shift past 2.when you put it in 2 it acts like it goes in for a second and the bike jerks then pops back and then back in. when you shift down from 3 it works fine as long as dont give it gas. what i mean you can use 2 to slow you down. so my question is whats the best way to go about fixing? i am mechanily inclined.