you can't take the intake grate off without removing the top deck, there is a nut from the inside of the hull on the front bolt, you need to take the pump off from the back, if you have Ibr you will have to remove the reverse gate assy. then you can remove steering nozzle and venturi and pump off as an assembly by removing the steering cable and the three bolts holding the pump on, you will likely need a new wear ring if you got an stone stuck in it and maybe a new impeller too, you may be able to clean it up if its not beat up too bad but it could be at the cost of loosing a little bit of performance.
P.S. you will need to tighten the bolts up on the intake grate again, if you can't get them to tighten up you will need to pull the top deck off to get at the nut! otherwise it could start to take on water.
P.S. you will need to tighten the bolts up on the intake grate again, if you can't get them to tighten up you will need to pull the top deck off to get at the nut! otherwise it could start to take on water.