Water test, take them out on the water and ride them. No water test, assume you're going to be restoring the entire ski. They should take off smooth, no bog, if it revs to 7k and goes no where the wear ring is probably shot. Compression test, if they both have the 951 engine you're looking for 130-135 psi per cylinder. If the gtx isn't the limited it would had the 787 engine and you'd be looking for 150 psi per cylinder. Regardless you're going to have to go thru the entire fuel system. If you're not mechanically inclined you might want to pass unless you had a local Seadoo mechanic as most dealers won't work on the older 2 stroke skis.
