Sekonic L-358 off by one stop

I bought a used L-358 that is underexposing one stop. I only realized this was the case (I thought I just liked one stop over) when I compared it with my friend's 358. I checked and the calibration +/- was 0.0. I've since set it to -1.0, but was wondering if there's anything else I can do.

Send it to Quality Light Metric in Los Angeles. All they do is repair and calibrate meters.