Originally Posted by Robert C

I have worked with that style of switches quite a bit. If the solder joints are good, then clean the switch with alcohol.

There instructions are generally for when the switch will not turn on; however, they may also work for "wont turn off"

Get some alcohol and q-tip style swab. Turn the switch so the button is pointing up. Then thoroughly wet the swab with alcohol. It should be nearly dripping. Then place the swab on the button and pres repeatedly and frantically. What you are trying to do is to fill the switch chamber with alcohol while repeatedly making and breaking contact. This is to clan any crud off the face of the contacts (like I said, this is normally for won't turn on).

Thinking about this, I have successfully done this for button switches that will not break contact.

I used to work on Copiers and the whole control panel is made up of these type of switches, under the cover. I used to have to repair these switches quite often.