Alternative to Digital Servo?
There are many ways to solve the problem. But most servos will "sing" when you apply a load to maintain the position, analog or digital. Here's a few ideas:


Use a second servo or a solenoid to apply a brake or locking mechanism. Pull the load up, apply the lock, then cut the power to the main servo. To lower the load, apply power to main servo, release the brake and lower the load servo.
Consider using an analog servo instead of cutting the power to a digital servo. By using an analog servo, you can simply stop sending the timing pulses and it will stop "hunting". This is more elegant than cutting power to a digital servo. However, no pulses means no power to the motor so you will still need a brake or lock otherwise your raised load will lower itself from gravity.
Use a sail winch servo. These have much higher gear ratios, do multiple rotations, and run slower. For example this 3.5 turn Hitech analog servo. By having a high gear ratio, the torque on the motor from lifting your load is small and not as likely to "sing". You will need to experiment to be sure because they don't publish very good specs for hobby servos. Again, you can stop sending the timing pulses to stop it from "singing", but it also stops power to the motor.
Use a DC motor with a gearbox and/or screw-drive mechanism and limit switches. One switch tells you you've hit the top limit, the other the bottom limit. You'll need a bridge using transistors or relays so you can reverse your DC motor rotation. Then you simply drive the DC motor forward until you hit the top limit switch. Or reverse the motor until you hit the bottom limit switch. Again, you can use high gear ratios or a screw-drive so that the motor cannot be moved by the load, or you can use a solenoid or servo brake/lock if you need lower gear ratios for speed. This type of mechanism is popular in American homes in the form of a garage door opener :)
Folks mentioned stepper motors, but those are usually big for the torque you might need, but might work for your application. They still need a switch or some way to calibrate the position (e.g. bang it to a stop).