FreeNAS ZFS Degradation assistance

I have a FreeNAS 11 replication setup the primary node is fully functional. The backup node shows a degraded zpool status but the HBA shows no issue. As of now the data appears to be intact. I want someone with more experience than myself to help me diagnose and identify the issue/cause. I will order and pay for parts (if any). Once needed parts arrive, the freelancer we select will need to work with us and our data center back to a healthy state. The data center staff can do the physical work but I need help developing and executing the proper repair plan. Remote work with the unit via SSH and HTTP will be required but NO onsite work with the equipment.