My son and I just restored a 78 Enticer. Had it out running a bunch on the lake this weekend, about halfway through, the belt started jumping and it appears like there is a bunch of rubber dust under the hood. It is the belt that was on it and the sled sat for 15 years. Are there clutch adjustments to be made? It takes off fine but when you go above 50% throttle, The belt jumps. I am new to sleds, any pointers would be welcome. Thanks!