Eventide Staff
To connect from S/PDIF to AES you need to connect pin 3 of the AES to S/PDIF ground and pin 2 of the AES to S/PDIF signal.(Or vice-versa). Pin 1 of the AES should be left unconnected.
Because this is a pretty simple cable, people usually make them themselves, so there are not many commercial ones available.
But be aware that this is not a guaranteed fix, although it may be helpful.
If you can generate an optical S/PDIF, this would be worth trying.