hello
you can remove just one switch, but its very tricky and you will likely crack or break the little tabs that hold in the switch. btdt
but i have also been able to remove just one switch without breaking the tabs..
if you do manage to remove one switch you can take it apart and clean it up and it will work.
that is if you can get it back together. usually no problem.
they get all gunked up inside.
sometimes if you rock it back and forth kinda hard it will start to work, not too hard.
use a very tiny screwdriver to hold back the tab on one side while pushing on the top of the switch lightly to help push the switch out part way, once part way out past one tab use the tiny screwdriver to un-latch the other tab.
best thing to do is practice at the junkyard.
good luck
mike