Simple LED Indicator Circuit for 120V AC Ball Feeder On/Off Status Monitoring

I'm looking for a simple circuit that monitors incoming AC power and turns a red led or green led based on whether the AC power is present or not. I have a ball feeder for a pitching machine that runs on 120v power. When it's turned on, it slowly rotates a small knob that slowly feeds balls into the machine. The goal is to have a red led light up when the unit is switched on and have a green light turn on when the unit is switched off (but it still is plugged into 120v AC outlet).  I want to let the batter know when the feeder is on (red led) or off (green led) so they can safely move around without getting hit by the ball. Very simple concept. Trying to do it the easiest way possible. The feeder unit is only 5" x 4" x 4" so I would like everything to fit into the existing box to keep it simple.  Thanks in advance. Dan

What parts are on the inside of this ball feeder?
From your description there must be a place for the AC to come in and a switch of some kind to turn it on and off. Also a motor to turn the knob. Probably a fuse as well.
You will need to power this circuit using the AC before the switch and you also need to detect if there is AC after the switch
Then you need to compare the voltage after the switch with what is before.
The problem is that this is AC and I'm more familiar with low voltage DC. Is there perhaps a circuit in there already that uses DC? Then maybe you could make use of that for part of it.
Sorry - so far only half-baked ideas here.

There are lots or examples like this https://www.youtube.com/watch?v=NTfKnhE58Yk on YouTube of contactless voltage detectors. Saves the safety problem of tapping into  the 120V circuit.