Thank you for your replies.
We checked all the rubbers, coupling etc they are fine. We went to he level of borrowing a Brovo II leg and she worked perfectly.
In regards the engine it's a MAG 350, 5.7L with a Bravo I leg. Propeller is a three blade, 19 inch. The boat is in the water on a mooring so I don't have any pics.
The mechanic is going to try another prop and see what that does.
I will keep you updated but thanks again for your responses.