[Mr V]

Without knowing more specifics about your set up it is hard to give appropriate suggestions. If there are gears in your lift then a servo that engages a parking pawl could be a viable option. One problem with a parking pawl is that it can become torque locked and require a lot of force to unlock it. This can be overcome by powering the motor to drive the lift up slightly while trying to unlock.

Depending on how many positions you wish to be able to hold in driving a "pin" through two elements with a solenoid or a power door lock motor is another option. Again you have the possibility of it being hard to remove but the same solution of driving the lift up slightly while pulling the pin should unlock it.