To remove keys from this keyboard assembly, first pull off the key stop.  It's at the rear of the keys and it runs the entire length of the keyboard.

Make a mark to identify its orientation.

With the key stop removed, push down on the rear of a key, then push back a little so it unhooks from a cutout in the metal key frame.  Here you see the key unhooked.

Notice the leaf spring in the middle of the photo.  This is the spring that forces a key back up after it's played.  This spring will lift the key up once its rear is unhooked.

This photo shows two black keys, one with a broken rear hook.  This is where these keys often fail, causing them to wobble, lean, or bind on adjacent keys.

Here's a look at a Korg M1 keyboard with the low C key removed.  The red tape marks the slot that receives one end of the key spring.

Before a black key can be removed, its adjacent white keys must be out.

This is the same key spring slot on a Yamaha MOTIF6.  It's a little different than the Korg but there's no difference in either the key or the key spring.

Here's the removed key and key spring.

Near the front of the key, the contact pusher sticks up.

In the Key Contacts Story, there's a photo of a key contact that's stuck on the wrong side of this pusher.