I know this has been mentioned before but my problem is slightly different to how it is reported by others so here is my specific description.

The output levels (mains, headphones, any output channel) is sometimes normal and at other times is barely audible. There is no consistency with when the levels will drop. It can happen any time during the day. Many days I sit down at the studio and it is working, then go get a coffee, come back, and the levels are down.

Other days it is quiet all day, and other days it works perfectly all day. It doesn't matter if I turn the unit off overnight or not, the issue can occur no matter what I do in this regard.

Totalmix and the front panel all look normal when the problem is occurring, i.e. the signal level indicators look normal even when the output volume is very low.

I ordered a replacement power supply and installed it, no problems. It worked consistently for 2 days after that, and then now it is back to the same problem.

Is there anything else to look at? I don't want to give up on this because I love the inteface so much.