Don't worry much about the sync.. 🙂
It works only at idle😉It smooths out the idle.Since you opened the throttle and above 1500 rpms around has no any effect!😉🙂
I had a good luck with that freeze spray on some cases.Heat didn't helped much.Anyway...He could try both heat and if doesn't help,then with the freeze spray..
The heat at that area will worse the things due to the expansion.The metal there will need contraction to remove the pins.A like this freeze spray will do the job i believe...
Repairable here with life time warranty
https://diag-engine.com/abs-pump-motorcycle/yamaha/2467-fjr-1300.html
If you buy a used one from ebay probably will have the same problem right now or in the short future..
Unfortunately the problem is inside the unit"Stucked valves"Caused if you don't change often the fluids every one or two years and if you don't activate often the unit by your self on a slippery road carefully.
Repairable here with lifetime warranty:Read the description..:
Email them for more...
Also remove the ECU connector and check the pins there for any corrosion.If the problem remains,then perhaps the ignition switch started to fail..Also on what colour wire/pin you found the green oxidation?Only on one or to all the connector pins if you remember?
Lift the tank and remove the T-bar.Under of it there you will find some connectors.Unplug them and check for corrosion on their pins.These connectors can cause a lot of troubles!Also unplug the ECU connector and check the pins if they are in good condition.Please let us know about..