Sustain pedals not working on Electro 3

[harmonizer]

Sustain pedals no longer work in my Electro 3 (version 3.12 firmware). This is a new problem that arose during the last few weeks.
We have tried two different sustain pedals, including one that works with my Roland FA-07.
We have tried changing the Electro 3 sustain pedal polarity setting from its usual "5.CL" setting to "5.OP".
None of the above helped.

We took the sustain pedal we had been using with my Electro 3 for the last 2 years and connected it to an extra M-Audio MIDI controller,
and then connected a MIDI 5-pin cable from the MIDI out jack of the M-Audio to the MIDI in on my Electro 3.
This allows the sustain function to work for notes played on the Electro 3.

I opened up my Electro 3 and found nothing obviously wrong mechanically. I even opened the small cover on the part of sustain jack which is inside the Electro 3, and saw that all the electrical connections with the 1/4" male jack from the sustain pedal look good.

Can anyone offer any suggestions for a potential fix?

[pterm]

I like your MIDI work-around.
So far your diagnostic method seems logical: Following the signal path into the Nord is the best method.
1. Is the pedal working (switch, cable, connector) - Yes, it works on Roland.
2. Is the Nord's receptacle jack working?
- this is impossible to confirm by visual inspection. --There could be an oxidation layer that limits the electrical signal level.
- Try cleaning the contact points within the Nord's connector using a cotton swab and isopropyl alcohol. -Be sure to discharge static electricity by touching the Nord's metal chassis before touching any electronics. Also take care to remove any stray cotton fibers.
- If you have an ohmmeter, use it to measure the resistance across the contact points.
3. Is the Nord's receptacle jack still connected properly to the circuit board?
- mechanical stress on the receptacle jack might fracture the solder causing an open or a high-resistance circuit.
- this was mentioned on the forum previously:
nord-piano-grand-forum-f10/broke-sustai ... ft#p130110
4. After this, diagnosing requires tracing signals on the circuit board. I recommend against this if you lack electronics diagnostic experience.

If this exceeds your available tools, comfort level, or abilities please take to a qualified repair shop. If you need help to proceed yourself, please ask.