What was found
(CAN) PILOT NOTED SLIGHT ENGINE VIBRATION, ENGINE PARAMETERS NORMAL .INVESTIGATION REVEALED EXHAUST SUPPORT MOUNT P/N 1250255-7 BROKEN, ALSO DISCOVERED MUFFLER (P/N 1250251-13) HEAT SHIELD MOUNT CRACKED AT WELD. EXHAUST SUPPORT MOUNT AND MUFFLER REPLACED, VIBRATION PROBLEM SOLVED. AIRCRAFT OPERATES ON FLOATS, SUSPECT THAT MOUNT FAILED AND ALLOWING MUFFLER, TAILPIPE TO RESONATE, CAUSING MUFFLER TO CRACK.