What was your use cycle? Once a week for 20 minutes? 24/7 from the time you got it until the time it died?
I bought an ultrasonic cleaner a couple of years ago...the idea was I'd use it to clean off AR BCGs and pistol parts while I tackled the stuff that was too big to fit into the basket. After a year of using it...it turned out I could still clean things faster and better manually. All that it really saved me was some patches and rags, and a little bit of elbow grease
And yeah, I could set it to clean and then take off for an hour and come back and the part would be mostly clean for me...but, the hard gunk was still hard gunk to get off.
Works great for cleaning brass though...having said that, even if I do use it to clean brass, I still throw the brass into a tumbler of crushed walnut shells afterwards anyway to give them a nice sheen. So again...it's not buying me too too much.
Either ultrasonic cleaners are a gimmick, or mine's shitty