Hi Mike,
Many Proxy switches have a red light indicating that they sense whatever is in place. Do you see a red light on either one of them? If you see a light on one, then command the shot pin to fire, does the other one light up? If not, that is a strong indication that the switch is either misaligned, dead, has a loose connection, or broken cable.
The M-Fin alarm usually means that a Proxy switch has not been activated after a certain time period defined by a parameter or in the ladder. If it happens during indexing as you mention in your other post, it is likely something to do with a "in place" sensor. This happened to me once on my Tsugami because I programmed a 36* index, but it only had 5* indexing (no full C axis), so when the shot pin fired it never found a groove to drop into and thus never activated the "in place" proxy switch. The machine would sit there for a few seconds then alarm out.
Can you tell me what M21/M22 is?
If you have a competent machine tech at your disposal, they can look in the ladder and see which switch is causing the alarm, then test the switch or cable.