Today my bike started to creak, then more, then really bad... full squawk 6 times on every pedal stroke.
The idler... pulled out the 3 bolts and the idler popped off. The inside bearing stayed in the frame. The ceramic bearings felt good but there was dust in there. Cleaned the dust from the idler surfaces and bearing inners, greased and back to silent.
I suppose this is going to be a regular maintenance job downside to have a free spinning idler.
Nearly 400km on the idler with no seals so not that bad, only took 10 mins max with grease and a 4mm Allen key.
At least I know what the signs are now and it deteriorates really quickly. Started yesterday with a slight noise then got gradually worse over the next 25km.
It's an embarrassing noise, like a completely trashed bottom bracket.