Thanks. I used my DMM and continuity check to confirm that the (+) side of all the caps in question definitely connect to the 5V rail. Because of that, I'm fairly certain that "6A" should be interpreted as 6.3V, especially in light of the physical dimensions of the existing capacitors. So with that in mind I am pondering suitable replacements.
Mouser has drop-in replacement electrolytics for about $0.50 each in 5pc quantities (
Panasonic EEE-FP0J220AR). They are rated at 2000h at 105°C and have a rather low 0.85-ohm ESR. I thought about tantalum (to avoid future leakage issues), but they are expensive and could go up in flames if you don't voltage spec them at 10V or 16V. That's why I am seriously pondering 10V 22uF Niobium Oxide replacements (
AVX NOJB226M010RWB). Mouser has them for $0.75 each in 5pc quantities. They won't burn, have only a 20% voltage derating (versus 50% for tantalum), and a low (but not too low) ESR of 700m-ohms. The only potential caveat is the small 1210 (3528) package size, which is a mere 3.5mm long. I've not yet removed a stock cap to see how close the pads are, but if they are close enough for a 3.5mm body then these Niobium caps may be the perfect replacement solution.