The owners manual clearly states that the drive system must be lubricated after each day of running. This is likely the cause of the high pitched sound. It does not require the drive shaft to be removed. The manual has four clear photos showing where to lube the drive system. Frictional heat and vibration from running the dry shaft could have loosened the stuffing tube in the hull, causing a leak.

Is the front of the driveshaft and motor not accessible?