Copied from my notes from #22 thread (personally this message board could be split up better but oh well)

You seem to be on the right track with the plt, and the pzt dials. But just for a little more input on them I will share what I know. As you already know you cant change them without switching the #8 switch on the back to unlock. (to the left) The plt (pitch limit trim) Will adjust the range of the servos, If you turn to the left the range of the servos decrease, and to the right increases the range, This will affect the lift, and if you make the range too big it will be hard to control your height, a slight movement of your throttle will send your heli up way too fast and when you chop the throttle it will slam down. Another thing to remember is if you make the angle of the blades too aggressive too fast than it will over work the motor, and will not get your blades up to the proper rpm, and cause it not to climb. It will also cause the heli to spin harder to the left because the blades have too much restriction with a lot of pitch and are not cutting through the air smooth. The pzt ( pitch zero trim) is important to set right also. You want your heli to began lift around 60-70% throttle, you can do this by your pzt knob by turning it to the left to increase pitch, and to the right to decrease pitch. Something to know is if you make your heli lift at too low rpm it will cause it not to get up to rpm and cause it to fly heavy, and when you try to increase the throttle it will actually loose rpm, and altitude, and because the pitch will increase and the rpm will decrease the heli will began to spin more to the left and you will have to correct more with the left stick. The speed of the blades also helps create a gyro affect, and the faster they spin will make the heli more stable, if your blades do not get up to speed, flight will be more unstable. If the blades spin too fast before lift off it will cause the tail motor not to keep up with the blades, and cause your heli to spin to the left also. Try to adjust it around 60-70% is about perfect for smooth flight.

author is not me...
Rob.