MacOS – Unsupported Macbook 4,1 (2008) on 10.10.5 (Supplementary) – No Audio After Update – What Next

NOTE: If you are not interested in how I got to this point, skip to the last paragraph.

As it currently stands, I have Mac OS X Yosemite running on my black Macbook 4,1. With the following kexts (in addition to the defaults provided by MacPostFactor), I was able to get OS X 10.10.2 running fully, with little-to-no issues:

• Intel GMA X3100 kexts (provided via an installer)
• IOAudioFamily.kext
• AppleHDA.kext
• Apple_iSight.kext

I also installed the NoSleep extension, the Software Update Patcher (not before learning the hard way), the AirDrop Enabler, and the System Font extension (which changes the system font to the one used by the Apple Watch). In order to enable the kexts, I had to pull up KextDropper and enter this in the Terminal:

• sudo nvram boot-args= kext-dev-mode=1

Everything (including Time Machine 🙂 worked fine without modification after the update to 10.10.2 – except for the fact that I can't change the screen brightness (battery killer status confirmed).

However, I did mention: "not before learning the hard way"…
In order to get to this version number, I had to update from 10.10.0, and when I did that update, I did it without the Software Update patcher. So, I ended up going into the Recovery Image, and deleting 'PlatformSupport.plist' from the Terminal (fun times?). Then, I rebooted into the fully-functioning 10.10.5 (Revision 1) OS X desktop. This, of course, was the easy part. I have now encountered the difficult part.

What I am here to ask about is something that occurred after my update to 10.10.5, Revision 2. When I updated to 10.10.5 (Revision 2 – Recovery Update), everything continued to work, except for one thing – the Macbook is now back to having no audio support. I checked the boot arguments, and that revealed nothing. The kexts I installed are still in '/System/Library/Extensions'. I don't know what happened.

The main question(s):

1) How can I get audio capabilities back for this version of OS X?

2) Should I simply update to El Capitan (from App Store update) instead?

Possibly related (but not identical in nature):

• "Apple Stack Xchange | Installing Yosemite on Unsupported Macbook 4,1"

• "MacRumors | Post by AtVusr, on Installing Yosemite on Unsupported Macbooks"

• "MacRumors | Post by a02, on Installing Yosemite on Unsupported Macbooks"

The last link was one of the first solutions I tested – Voodoo audio kext(s) weren't able to fix this 🙁