MOTU Ultralite preamps dying?

[Cheeky]

Hi guys,
I have some issue I'd like to gripe about
I have an original MOTU Ultralite that I use for home recording (just a guitar, keyboard and a couple of mics).
I always kept the pad switches at middle position and I remember the volume was sufficient.
However, recently I began getting very low volume levels from both preamps, so I had to flip the pad switches to low (+24 dB) position.
That made the volume ok again.

BUT.
now it's low again. I have to use the gain option in CueMix (TRIM) to get a decent volume from the mics.
The hardware setup is fine, there's nothing wrong that could cause this loss of volume.
Both mics are Shure 58A Betas, using the different cables, so the problem must lie elsewhere.

I presume that for some mysterious reason the preamps are dying. However I haven't found any similar reports on either MOTU website or through Google.
Any ideas what might cause this?

[mcoyles]

How is it being powered? Own mains cable, or power-over-firewire?

[Cheeky]

How is it being powered? Own mains cable, or power-over-firewire?

it is powered via firewire
if you think that's the problem, I'm gonna try it with AC adapter on my notebook that has unpowered firewire port..