My friend is having troubles with his Polaris Clutch. Its a 96 xlt 600. It may be an SP if that makes a diff. Right now his cltuch will begin to engage at 6000rpm. Once it starts to engages the primary backs off and it slaps the belt. Lurching forward alittle bit each time its slaps. He asked me to take a look at it so what should i look for? Also it used to engage at about 4500 so its progressively gotten worse. Im thinknig maybe some bad springs??