Hydraulic servicing. I know this debate has gone on for awhile, but my current airframe has now reached it's limit. Sys A is sitting at 39% quantity and the low pressure light is on; I have been unable to clear it through the maintenance screens on the CDU (even after a panel state reload). Arming/activating the QTY low failure on SYS A and "fixing it" doesn't do the trick. So how do we service the HYD fluid levels? What is the EXACT procedure?