AW hub noise

I just gave my 3 speed sturmey AG dynohub (internally an AW) a service. I'd been having an intermittent clunking noise, maybe once a ride, and I'd assumed it was the clutch slipping under load, hey ho it's an old hub. So I opened it up, gave it a clean, replaced the clutch and pawl springs, and put it back together. I took it for a test ride and it's now clunking every half turn of the pedals, in all 3 positions and worsens under load. Before the clunk there is noticeable resistance for a moment. Freewheels fine.

I'd love any thoughts. Most other posts I've read about noise are grinding or just the pawls clicking. I'm stumped.

I'll be reopening the hub tonight to check I've reassembled correctly. As this was the 3rd time I've serviced this hub, I wouldn't be surprised if I'd got flippant.