Hi Guys,
Just a suggestion, check the alignment of the flex cable. When I am servicing my boat, I re-install the flex shaft by making sure that the shaft can be pushed into the boat from the transome all the way to the collet without any obstruction or mis-alignment. It might take a little pressure to push it into the collet, but this should be normal, from my experience. Then check the clearance around the prop shaft for flex shaft contraction.(flex shaft expands when it spins)
On the metal props, just make sure the pitch is about the same as the plastic one you are replacing. That's what I did before I ordered one. The one I bought was Aquacraft GrimRacer 36x55. P.N. AQUB9700 2-blade
Going to try three blade for more speed.[8D]