On the BSC2 HEPI system, the valve of on actuator V4 was changed on june 25. When trying to identify the source of the problem, the fluid flow was stopped at the problematic actuator. Then, we saw a huge change in the actuator positionning indicating there was an issue with the valve (No drive - flow vs No flow). Yesterday, we stopped the flow on all actuators and looked for large changes (comparing the No drive - flow vs No flow configurations). Some minor changes were seen but nothing is alarming.
The attachment shows the position changes (seen by the IPSs) when stopping/starting the flow. (units 650counts/mil).