If you put WLC #1 in Master Controller Mode I don't think the AP's will try to migrate to WLC #2 when it comes back on-line. Just make sure you return WLC #1 to normal operating mode once you are complete.
If you log on to the controller using HTTP & go to the Wireless tab you will see all the associated APs. If you click on one of the listed you will see the details for that AP. On this screen, you can specify which controller you want this particular AP to prefer. You can specify up to three controllers.
Transferring Crash file from standby: Login to the Active WLC in HA.
From CLI: (Cisco Controller) >transfer upload datatype crash (Cisco
Controller) >transfer upload filename (Cisco
Controller) >transfer upload mode tftp (Cisco Controller) >transfer
This is the start of a display filter cross reference between Wireshark
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