I have a 2003 Seadoo GTI LE-RFI. Yesterday evening was running near full throttle at 52mph when rpm drop and speed drops to upper 30's. By the time I got back couple to dock after couple of miles, top speed was 20mph. put ski on lift and nothing around impeller. Can get full rpm's when on lift but as soon as lowered into water it Boggs down to about 850rpm under the load of water. Friend has said engine is llkely "blown" and needs to be rebuilt or replaced. Any other suggestions