If your M11 isn't centering it could be for a few reasons...

1. The steering tension is set too loose and the springs don't have enough tension to return the steering to center. You can view this on the steering D/R screen. Fix = tighten the steering adjustment 1/2 turn at a time until it centers better.

2. The bearing could be dirty and would need to be cleaned. Normally, this only affects the movement and not the centering capabilities of the radio.

3. The radio could need to be calibrated if it has a lot of hours on it (maybe 75 or so). This could also happen with severe weather changes that the radio experiences. If it's in the extreme heat and then the following month it's in freezing weather. This could happen with any radio brand. Fix = send in for service calibration.

Either reason it's not that big a deal. Not sure why it took six weeks to service a radio. Most people I know say it takes about a week or two.