X5 ballast replacement - 1 or both? New or used?

[N S]

Need to swap the ballast out of the driver side. Would you do both driver and passenger at the same time or leave the working unit alone?

Would you buy new or used ballasts? Any recommendations on where to buy from?

Swapped out bulbs and that didn't fix my problem, though the driver side bulb was significantly more cloudy than the passenger

[Dking078]

One ballast is fine. Used is like anything else.. A gamble. But the savings is usually worth it.

[N S]

Thanks. Just ordered used.