The "dragged MP3 files straight onto it" part is the real trick. Those old iPods show up as a plain USB drive when you flip the setting, so the computer just sees a folder full of music instead of some locked down device. I did the same thing with a Sansa Clip and a Creative Zen back in the day, and the only thing that ever bit me was album art and playlists not showing up unless you got the folder names right. Six hours of battery on a 2006 model is honestly kind of amazing, mine started dying after 4 by 2012.

Two years at 80 psi is wild but I get it. I ran my old Binks at whatever the guy I bought it from had it set to for probably three years, turned out to be 65 psi on a gun that wanted 25. My clear coat looked like an orange peel every single time and I just kept blaming the cheap clear. Finally my buddy Dale grabbed my regulator and about had a heart attack, dialed it down to 26 and the next panel came out slick as glass. Now I check it every single time I pick up the gun, takes two seconds and saves me an hour of wet sanding. You are not alone on this one, seems like half the guys I know never touch that knob once it is set.