My wife's sled...a 600 mountain max (with only 2k miles) recently had an issue. One cylinder cut out, and upon inspection found the plug tip flattened and bits of metal jammed in plug. Compression test was fine, but pulled jug to find source of metal. About 2 square inches of the rear piston skirt was broke off and missing. It appears all the pieces were ejected through the exhaust eventually, because I don't see any pieces in the crankcase bottom. The jug appears fine also...no scoring. My question is: first what would cause the breakage, and most importantly, should I go ahead and split the case to look for any pieces....is there any place for pieces to hide? Or maybe I could pull motor and invert and flush out somehow. I want to pull motor to inspect case bottom anyway....