I used the heatgun in the same way as you but I warmed it up with the first setting and switched then to the second(500°C)
Well when the solder melted the capacitor is kind of swimming in the solder and as you are moving the heatgun around the whole time it kind of vibrates and slowly moves a bit because of the airflow.
You can compare it to a ripple of water when you blow at it...
You gotta stop then because otherwise it might move too far and then you will have to put it back in place...
it really takes a while so be patient and keep watching the bigger capacitors...
I guess I overdid it though because the color of the solder changed so be careful.
When I get my next E74 I will record a video...
The area depends as well putting pressure on the ana-chip fixed my first 360 so I concentrated on the ana-chip which fixed it.
This one was different though nothing brought it back to life so I heatgunned the area from the whole anachip over to the GPU from both sides.
After that it worked finally
That's essentially what I did - I heated the ANA chip and both side of the GPU, using circular motions about an inch or two off the board. I used alot higher setting than you guys did however - my heat gun goes anywhere from 300 - 1350C - I switched mine to the 1200 setting and only hit my board with it for about 1 minute total time between both sides of the GPU and the ANA chip - make sure to KEEP THE GUN moving or else stuff will fry - I never waited to 'see' the solder melt, I just assumed it would and that 1 minute at that high of a setting would be more than enough.
My settings may have been overkill, but you want solder to only be heated for a small amount of time or the discoloration will occur, so I pretty much just guaranteed that I could bring it up to melting temp very quickly.
...again, just my two cents.
Good luck everyone!