Seems like its common knowledge that the power supplies for the Solo are poor. I'm on my 3rd in 18 months. Almost everyone recognises its an issue, apart from Sling. All the issues I've had with the Solo, mainly around losing network connectivity (i.e. the network lights are not on, even though power is) have been caused by these faulty adapters.
I'm in the hunt for a new supply again. Rather than go with the Sling version I've found an alternative here (UK):-
Meets the 5V 4A power requirements and hopefully one of the "tips" will fit the Solo. I'll post back when I receive it.