Over the summer I purchased two used rev 600HO's. One is an 03 and the other is an 04. Both sleds will surge from 4800rpm to 52 to 5400rpm . They will not hold steady above 4800 without jumping on up to 5200-5400rpm. Is this normal for the 600HO? Could there be a clutch problem? Neither sled is SDI and the 04 is the worst of the two. Any help would be appreciated!!