So, the ports 47 and 48 are the VPLS service ports connected to the Juniper devices right? If that is true, the fields that would be used by switch for hashing would be the source-mac-addresses and destination-mac-addresses (only L2 fields).
If it is only VPLS service traffic flowing out of these ports to the Juniper devices, the only option would be to use the L2 algorithm rather than L3. But if there is not a lot of source and destination mac address variation, this may not help.
If the traffic is coming into the switch through multiple ports, we could give port-based sharing a try.