[Al_The_Man]

One possible problem I can see already is the encoder has SIX wires not FOUR? Could be older technology?

The common encoder connection count is either 8 for differential encoders and 5 for single ended. if you have 6, it could be the 5 plus a shield or case ground.
If they are DRC encoders like the one in your picture, the connections should be readily available.
I assumed you have included the encoder power connections in the wire count?
Al.