Remotes working sporatically

Your description suggests bad/dirty contacts inside the remotes and jammed volume buttons on one of them. Cleaning the rubber pads and the circuit boards on all of the remotes might solve the problem.
Use some ethyl or isopropyl alcohol and cottonwool to clean them.

By the way, here's a nice way to test a remote using your mobile phone's camera:

Turn the camera on, point the remote towards the camera lens so you can see it on the mobile's display.

Look at the display on your mobile phone and press buttons on your remote - you should see bluish/greenish flashes from your remote's emmiter each time you press a button on the remote (the camera on your mobile shows infrared light from the remote as visible light on the display - if it doesn't do so in the normal mode, try the night mode for the camera instead).

If you press a button and there are no flashes, that button probably has a bad/dirty contact.

if the remote is making flashes even when the buttons are released, this means that a button is jammed (you need to clean the rubber pads and the housing, especially the holes where the buttons come through as there's probably some dirt that keeps the button pressed in, which causes the volume to go up/down all by itself).

hope this helps...

regards

3rq8 (Triarcuate)