You may want to check if the teeth are meshing. If not, loosen the main motor screw and move it closer to the main gear.

As for the screeching, it may be a bit early for this, but it could be the bearings along your main rotor shaft. I know that going from stock to new bearings quieted it down significantly. Check out any bearings that are 6x10x3mm and that aren't the stock bearings. I bought these [link=http://www.hobbypeople.net/gallery/256965.asp]XTM Racing[/link] bearings from my hobby shop.