I started to notice distortion that obviously wasn't in my mixes. A sine sweep soon revealed how bad they were. The lows showed it more comprehensibly. It was intermittent but loud and ugly

At first I thought it might be due to the black cloth covering being worn and vibrating but removing it altogether didn't fix the issue. There is another white covering that looks a bit loose but its a mystery and I have consigned them to the useless gear bin.
Checked out the headphone thread on this forum and nearly went with the ATH-M50Xs but found another set of DT770s for 200 Aussie dollars. If they last 10 years like the old ones that works out to $20 a year. I can live with that.