Remove the 21 bar cover

Remove the cover and bars of a 21 bar Oscar Schmidt:

Not a bad idea to take a digital picture of your setup, just in case.
Remove the four screws, put them in a tuna can with a refrigerator magnet.
Lift slowly from one end, while pushing the buttons down with a pencil erasure.
Lift the bars by grasping each end, lift up just high enough to clear the guide pins, then move the bar laterally. This forces the springs to drop back in place on the pins.
Set the bars in order to the side. Most bars are marked at the treble end. If not, mark them now so if they get scrambled you can reassemble the set.
Reverse the process to reassemble, using the pencil erasure to “herd” the buttons back in place as you drop the cover down.