 The thrusters that give problems are on a part of the capsule that does not come back to Earth. It's called the surface module. It will burn up in the atmosphere. So they won't get those thrusters back to look at them. So the more data they can develop before they return to Earth, the better in trying to understand what caused the problem and fixing it. So that's one reason. And the second reason is this capsule is designed and is supposed to be able to stay up on ISS for six months.