Years ago I bought a well-used 96 GTX with the 787, and within weeks lost the engine due to a balance shaft bearing failure, probably from poor quality 2-cycle oil of the previous owner, and also demonstrating front cylinder hydro-lock typical of a deteriorating crank seal. These subjects have all been discussed. Upon rebuild I now religiously use SeaDoo XPS 2tek synthetic for seal conditioning, and make sure the oil in the sump is controlled with a one-way squeeze bulb with 1/2" fittings and the valve etemplet shows above. Yes, a little overkill but piece of mind when I ski on primitive lakes in N Idaho. No problems 8 yrs later.