I’ve taken it apart and found nothing visibly wrong, as did my LBS. Basically, there is no difference between engaged and normal position – anyone else had this?

Contacted German retailer, who are happy to return it to Shimano Germany, but turn-around is 4 to 5 weeks! So I guess I’ll have to buy another one and potentially get a second under warranty

http://www.bikeradar.com/mtb/gear/article/trail-tech-how-to-adjust-a-shimano-shadow-plus-rear-derailleur–36461/

did that – it’s fully wound in and still doing nothing!

Email Madison about it. They replaced mine in the same circumstances and told me to return it through my LBS with a proof of purchase. Turnaround was about 2 weeks. Warranty@madison.co.uk

I bet it’s the thin circular bit of metal that tensions the clutch that’s snapped. It’s a known issue and happened to mine recently. Sent back to tweeks cycles and then to shimano who sent me a knew mech. Expect it will happen again though- part too thin to handle the forces.

Madison replaced jockey wheel on my German purchased one no questions asked