If you have not already done so, there was a foam rubber strip about an inch thick on top of the array of small circuit boards near the stop tabs. If this does not fix it, look for broken wires leading to the stiff wire. Operate the tab a few dozen times, and it should become reliable. Then use Deoxit D-5 to clean the contact. First, make sure the stiff wire for this tab is properly in the slot. The fine wires run through slot(s) in the rear of the plastic stop tab. The stop tabs move fine, stiff wires that touch against a contact bar.
Anybody ever had this problem?The trouble with the Flute tab that won't turn off is caused by a dirty contact on that tab. So its always on no matter if I lift or drop the switch. There is one 2' flute tab on an upper manual that won't turn off.