Many thanks for the help and information much appreciated just to confirm from the top of the edge conector top isxground 5 th down is 5volt are the 4 conectors left the data thats 2/3/4/6 have i got that right. 
Sorry, I didn't phrase part of that last post clearly.

There are 6 contacts on the edge connector, with a total of 4 wires connected. (5v, ground, and 2 data lines)
Edge connector (top is 1)
1. Ground
2. ?
3. ?
4. ?
5. 5v
6. Not used (dead end trace)
The two data lines connect to 2, 3, or 4.
Your board is probably wired with data lines on 3 and 4 like the optical boards in
Off Road (pgs 13-15) -- similar looking, but different part number.

To verify:
1. Connect 5v and ground to your optical encoder.
2. Set your multimeter to volts.
3. Probe 2, 3, or 4 while slowly turning the encoder wheel.
4. A data line will alternate between logic high (~3-5v) and logic low (~0-2v) as the teeth and gaps in the encoder wheel block and pass the IR light.
If you don't see changing voltages, you may have a burned out opto-coupler -- look for the IR LED light using a digital camera/cell phone camera. (they pick up IR wavelengths)
Scott