If a button on your Evolver Desktop stops responding correctly, i.e. it still works but it doesn't work every time or you have to press the button harder to get it to respond it is usually one of two things: either the switch needs to be cleaned or the switch cap is cracked.
The buttons on the Evolver Desktop are self cleaning. Because of this, often you may be able to clear up the intermittent operation by pressing on the button *hard* 50-100 times.
If that doesn't work, you may have a cracked switch cap (the switch itself is usually fine in this case). The crack is usually a very small hairline crack running vertically along the body of the switch. To troubleshoot this, you can remove the main board from the enclosure and swap the switch cap in question with a cap from a neighboring parameter. Removing the main board in the Evolver Desktop is an easy procedure involving only a screwdriver:
1. First remove the knobs by pulling straight up.
2. Now unscrew the 6 exterior screws on the case, which are 3 screws on the back and 3 screws on the bottom front edge.
3. Once inside, the main board is held in with another 6 screws. Unscrew them to get the board out (Do not remove the smaller, lower screw, to the right of the Left In jack).
Now that you have access to the front of the main board, remove the switch cap in question by by pulling straight up (no twisting required). Remove the switch cap from a neighboring parameter and place it on the switch you were having trouble with and try it out a few times. If the button response improved, the original switch cap is likely cracked and should be inspected and replaced (you can also see if the "poor" behavior followed the original switch cap to the new location). If the button response did not improve, you will likely need to replace the switch itself.
You can contact support for further assistance, and the unit can be reassembled in the reverse order.