Where can I buy a tail rotor motor for my protocol sb 3.5 channel

Double check that a strand of hair is not in the motor.. remove propeller and slide hair off if it exist. Happened to me and it was hair.

adjust the trim on the controller please watch some beginners videos. In this instance the problem is yaw which is left and right rotation on a helicopter it is affected by the speed of rotation of the tail rotor relative to the speed of main rotor and its gyroscopic effect. the floor cause weird flight effects on helicopters to get the trim precisely set it must be at least 4ft from the ground. but initially just get it to where it is controllable.

Is the channel frequency the same?

Check the rudder - tail trim

the black wire is a ground connection follow the power till you see the -
+ - follow the minus sign till you reach near the red wire that goes to the tail motor and solder it or even next to the power - whtch ts the ground part

Turn on Heli first then remote. power up rotor... hear beep. Now you are ready to fly.

you can try amazon, but if your tail rotor is not spinning you should take off the canopy and make sure the leads are well connected,and if they are then get your self a new PCB Board,and if you just purchased it just return it, but if you had it for a while then follow the steps above good luck...

I have added a quarter to the tip of my dh9118 and slid the battery a bit forward to give it a center like balnce

Maybe the rear rotor needs to be changed. These motors have a limited life especially if it's not brushless.

THE TAIL MOTOR IS NOT WORKING PROPERLY OR NOT AT ALL. YOU MAY NEED TO REPLACE IT