Common problem. With your 60 degree toss you are stopping your tossing arm, somewhat abruptly, shortly after your ball release. It's almost as if you are chucking the ball, or heaving the ball, up into the air. It should be more like you are lifting
the ball or placing
it into the air rather than throwing into the air.
Start the upward motion of the toss with the tossing hand close to your front thigh. Lift the arm up at an even, moderate pace. The speed of the tossing arm should be just fast enough to get the toss height that you desire. Release the ball just as your arm goes past parallel (to the ground). You can use your chin level or some other appropriate reference for your release. Just open your fingers to release the ball. Let your hand/fingers follow the released ball until your arm is vertical.
You should not be lifting your arm in the direction of the intended target area. You could lift your arm parallel (or nearly parallel) to the baseline as many elite servers do. If this is too extreme for you, try lifting it at some intermediate angle wrt to baseline -- perhaps 30 degrees to 45 degrees.
Execute a lot of practice tosses (w/o swinging at it). Toss so that the released ball follows a slight arc that you can catch in your outstretched hand (vertical arm). This would represent a good toss (particularly for a 2nd serve). Toss and catch in this manner until you develop a consistent toss.
You might try the Federer "ice cream cone" toss. His lifts his hand so that it is more on the side of the ball rather than underneath it. This technique should help to prevent you from flipping your wrist (or bending your elbow) as you lift/release the ball. The lifting action should should be from the shoulder (w/o bending other parts of the arm).