[FTC]: Problem holding motor in fixed position for jointed arm

[FTC5096]

We have a jointed arm connected by gears to a motor on our chassis. We are having difficulty holding the arm in position. Once the arm gets to the desired position and the motor power is reduced to zero, the weight of the arm causes it to fall. We tried using an encoder with the nMotorEncoderTarget command, but the motor stalls out before it gets to the desired position. We tried using servos, but they are not strong enough to lift our arm.

Can anyone offer a programming and/or hardware solution to hold a motor in a fixed position?