Ive got a TV going into an alcove and there is a picture lift mechanism over the TV / alcove.

For ease of maintenance id like the TV to be on a manual pull out bracket.

But i can for see someone opening the picture lift, moving the TV and then forgetting to put it back, closing the picture lift and then breaking things.

I was wondering if anyones come across a lockable TV bbracket so it can be locked in position and moved only by releasing it first.

Ive seen some marine mount have this feature but they are super expensive c. $600+.

Is there a more cost effect solution ?

Assuming you can push the mount all the way to the close position = drill a hole down thru the top lip of the piece that attaches to the wall. Then continue drilling that hole down into the arm.
Now when the mount is pushed all the way to the wall, insert a metal dowel into the hole and that will lock it into place.

Control system involved?? If so, you can use some photocell beam sensors.

If the beam is blocked, don't allow the picture lift to go down.