Is the encoder a coupled type or a through-hole type, the former would normally have a make/model on it.
I would hazard a guess that the other two in the centre are tach, they should be easy to follow and identify, tach's are not used now on modern drives so they could be left unconnected.
The encoder wires would normally have a Blk & Red for power and the rest could be detected by 'scope,
Check to see if there is any info on the encoder as I had a lot of info on some of the encoders fitted.
Al.