He decided to have his arm set at an angle so that he could keep playing the guitar.

VOA: special.2009.09.27

Merely moving a few feet to poke a rock could take three days, with the rover snapping pictures of its arm from every angle.

NEWYORKER: The Martian Chroniclers

The Solbot, made by startup QBotix, stops at each array and extends a cylindrical arm to adjust the angle of the photovoltaic panels so they capture the most amount of sun as it moves across the sky and through the seasons.

FORBES: How Robots Are Making Solar Power Cheaper

Opportunity has a sore shoulder in its robotic arm, and one of its wheels is stuck at a slight angle so the rover handles more like a wobbly shopping cart.

NPR: Mars Rover Marks Second Anniversary of Landing