to stop cnc magazine at position for tool change

Kindly, we are running the below cnc machine, after finishing a control and servodrives upgrade.
But, we are having some problems to stop the tool magazine at the exact position for tool change.
It is rotated by an hydraulic motor, which is controlled by hydraulic valves, making it very difficult to control the stoppage position.
Have you seen any cnc tool change similar to this one?
Any hydraulic recommendations?

MAZAK AJV-18N CNC Vertical Machining Center
http://www.gaec.com/catalog/machines/k13587.htm

Yamazaki AJV18N
https://www.youtube.com/results?search_query=yamazaki+AJV18N
(2nd 3rd ... videos)

index motor
EIS 160-2PC-2AH0-LL
valve
SL-G01-A3X-GRT-C1-9320B
valve
SL-G01-C5-GR-C1-9320B

Maybe you need a proportional valve and position controller. Plus position feedback sensor.

http://www.airhydraulics.com/en-us/products/rotaryindextables/rotaryindexingtableanimation.aspx
solved by running the valves in a way to have the pin goes inside the index to lock the hydraulic motor at a precise position, similar to the above link.
the index motor has inside the option to do this.
thank you