Gremlins ?
From Wiki:
Juno uses a bipropellant LEROS 1b main engine, manufactured by Moog Inc in Westcott, Buckinghamshire in England.[83] It uses hydrazine and nitrogen tetroxide for propulsion and provides a thrust of 645 newtons. The engine bell is enclosed in a debris shield fixed to the spacecraft body, and is used for major burns. For control of the vehicle’s orientation (attitude control) and to perform trajectory correction maneuvers, Juno utilizes a monopropellant reaction control system (RCS) consisting of twelve small thrusters that are mounted on four engine modules.[79]
Moog is an American company and has a lot of experience with spacecraft.
Good thing they decided to leave Juno where it is.
Moving it would have been a real PIA!
I wonder how much roadside assistance will cost