I found a way to wrap the cord that applied the correct kind of pressure to keep both speakers working, which mostly worked for a couple weeks but then as expected started to fail consistently as the cord continued to degrade. I also noticed that the speaker would often cut in or out when i was accelerating, decelerating, or going around corners. Obviously such maneuvers will apply a force to the cable, but it seemed a little odd that such a small force would affect it that much.
Last weekend i finally got fed up enough to call up the local Al & Ed's Automail, er, i mean Autosound, and ask them about time and cost estimates for repairs. (Since i originally got the device installed at the Huntington Beach branch of the chain.)
They said they'd have to look at it to determine the right kind of cable i'd need, but they estimated $30-60 for the cable and $80-90 for the labor. So $110-150 total. While i was at it i asked about the cost to replace the speakers, since one of them has gotten a little buzzy, and although i forget the exact amount i believe it came out to $200-250.
The speaker price seemed about in line with what i'd expect, but the cost to replace a single cable seemed a little steep. So i decided to try taking a look at it myself. I had vague memories of what they did to install the box in the first place, so i went down to my car and started poking around.
I had to check a couple web pages on my phone, but it was pretty easy to get the lower right glove compartment pried out and then the right air vent panel removed, which let me peer into the area where the component was but not really access it.
Unfortunately removing any of the stuff from the center panel would mean undoing screws on both sides which were covered by the air vent panels, and removing the left air vent panel would require removing both the top and bottom around the steering wheel. I considered giving up at that point, but after some encouragement from sithjawa and re-checking the online videos i decided to give it a go.
So i removed the two big panels, and then the left air vent panel, all of which were kind of hanging off the car because they had wires attached that i didn't want to remove, which let me get to the screws.
I removed the lower center panel which revealed a crack large enough for me to see into the area with the component but not large enough to reach through. At that point in order to remove the stereo itself i would first have to remove the video system, which was attached with larger bolts then the other components had. I wasn't sure if i had any screwdrivers large enough to handle those bolts (up until that point i'd gotten by with my pocket knife) and even if i could the video system has a half dozen wires plugged into the back and it wasn't clear from the videos if i'd be able to get away with not unplugging all of them, which seemed like a real pain.
So all i really had to work with was the original hole i had uncovered by removing the glove box. By wedging my hand in there and with a little bit of peering through the crack below the central panel, i was able to feel the along the audio cord but not quite reach the component. However what i _could_ feel was that the audio cord seemed to split up. Which meant that even if i could get at the device the 3.5mm to 3.5mm cord i had on hand wasn't going to work.
I was just about to give up when Avalyn came down to the garage to see how i was doing. Since she has smaller hands than me she volunteered to give it a try. I was reluctant about that because i would feel bad if she managed to scrape up her hands trying to fix my car, but she was able to reach in far enough to grab the box and drag it over to the edge of the compartment where we could see it through the hole.
Once it was there we could see that the audio cable was one of those 3.5mm to RCA red/white jack cables. I was still tempted to give up since i didn't have the right cable, but it looked like now that it had been moved i could _probably_ get a new cable plugged in with a little work.
We debated where to go for a bit, considering the Staples within walking distance vs the Radio Shack up by the mall. Then i did a search to find if there were any other closer Radio Shacks and we were surprised to discover there was one on Wilshire, right across the street from our favorite Japanese restaurant within walking distance!
So we walked over to Radio Shack, where we bought an appropriate cable for just under $10. While we were there we also noticed there was a Fatburger in the same lot, which may come in useful in the future. Then we walked across the street and had dinner at the Japanese place before heading home.
It took a couple tries but i eventually managed to get the new cord plugged into the box. And although the crack below the central panel hadn't really helped with getting the box out it was useful both for holding the box in in place while plugging in the cables and for threading the other end of the audio cable up through the hole in the back of the central compartment, so at least all the work put into disassembling the left side of the car wasn't a complete waste.
All in all i spent about 2 hours taking the car apart before we left to get the cable and then about 45 minutes plugging things in and putting the car back together. Probably about 3 hours total, plus $10 for a cable, instead of paying $110-$150. So arguably worth it from a strict economic standpoint :)
And of course, as is inevitably the case, when i finished putting all the panels back on i discovered i had one screw left over =P
Here is a picture of the situation around the point i was thinking of giving up. Although a flash picture from inside the car on my crappy phone camera didn't really come out too well: