Damn, serves me right for tearing into my battery pack before checking around to see that it's the charger that's likely the culprit. My recently purchased solo worked for about 4 days before refusing to charge with the light-show. I was convinced that it was the battery, and am now running on a couple of trustfires jury-rigged into an external pack while I await my 3400mah batteries.
Seeing the info here today, I metered my solo's wall-wart and it wavers from 10.x - 12 volts, which seems to indicate that it was the problem all along. Oh well, lesson learned.
A question for those folks that have replaced their batteries: Are you running unprotected cells with or without a 2-cell protection circuit? The stock pack was unprotected cells with a 2-cell protection circuit, that's why I ask. I ordered a protection circuit, but if folks are having good success without one, then I'll skip it.