JPMorgan Chase & Co. (NYSE:JPM)’s legal troubles show no sign of letting up. Richard Usher, the bank’s lead currency dealer London has been placed on leave as regulators investigate possible foreign exchange market manipulation, report Gavin Finch, Liam Vaughan, and Ambereen Choudhury for Bloomberg. Usher hasn’t been officially been charged and he is officially on leave, not suspended, but he has been away for two weeks and at this point no one knows when or if he’ll go back to work. The investigation centers on an IM group of senior traders at Barclays PLC (NYSE:BCS) (LON:BARC), Citigroup Inc (NYSE:C), Royal…