Unavoidable HDMI recording audio glitches and their fix

Been noticing some unavoidable noise when capturing from a certain HDMI source. It always sounds like scrunching up a newspaper, happens about once per 20 minutes (if at all), and looks like this in Audacity:

And this:

I don't ever hear it watching live; it's just in the recording. I've found ripping the raw wav and loading it in Audacity is both the best way to find the glitch at all, as well as the only way to fix it. So at this point I recapture and get a clip of the audio without the glitch, and replace this audio. 

This is already zoomed in, but I like to zoom in even further, to the point where the thin lines of the waveform become thick again. Then I just line up the audio and mute out the bad portion. It's sort of touch-and-go at this point; it's not as easy as it should be. I try to find an identifiable peak on the main audio and split there, then on the clean audio make the same split, trim, then snap and move. Maybe mute where necessary and then Track > Mix > Mix and Render. 

In AviSynth, I load like this: 

rawfile1v=LWLibavVideoSource("Untitled 115.avi")
rawfile1a=LWLibavAudioSource("Untitled 115 fixed.wav")
AudioDubEx(rawfile1v, rawfile1a)
stream1=last
rawfile1=last

Another problem I had was Blackmagic Media Express not recognizing audio from certain sources, such as:

• RetroTINK-5X Pro into OSSC Pro (individually, both scalers would work fine)

• EZCOO 4K splitter with manual downscaling

• RetroTINK-4K Pro with HDMI input, e.g. PSTV + splitter (even if I would get audio from a component source into the RT4K just fine)

My solution was to run the HDMI output into an HDMI + Audio Converter box, connect that to an HDMI Audio Embedder using a S/PDIF optical cable, and then finally to the capture card. 
My equipment chain, for the curious. And might I add, Google Drawings was plenty enough for this. Just had to set the canvas to a reasonable size in File > Page Setup (I chose 4K resolution, or 3840 × 2160) and set the measurements to pixels instead of inches, and everything else was easy to understand. 

I can't believe I wasted time dabbling with Lucidchart which limited the number of shapes I could use and wanted me to pay per month... and they wanted me to pay more per month if I wanted to pay for a whole year! Got rid of that app's permission real fast. 

AutoHotkey mouse movement script for precise scrubbing:

/*
up: Y -
down: Y +
left: X -
right: X +
*/

/*

space::Lbutton
; Hold spacebar to simulate holding left mouse click

Up::
CoordMode, Mouse, Screen
MouseMove, 0, -1, 0, R
return
;move mouse one pixel up

Down::
CoordMode, Mouse, Screen
MouseMove, 0, 1, 0, R
return
;move mouse one pixel down

Left::
CoordMode, Mouse, Screen
MouseMove, -1, 0, 0, R
return
;move mouse one pixel left

Right::
CoordMode, Mouse, Screen
MouseMove, 1, 0, 0, R
return
;move mouse one pixel right 
*/

~Tab & NumpadEnter::
Send {Click}
return
;click