Scarab 165 not going into gear

[Lakeside]

Hi! My Son was driving our Scarab 165 across the lake and it stopped going into gear. It will idol. I checked the reverse gate and did not see anything in there. When I move the shifter I can see the gate go up and down. Any ideas?
Thank you in advance!

 

[Cobra Jet Steering LLC]

Probably loaded the pump with trash and you are cavitating check the intake and jet pump