Thanks, @Bruno and @Ben!
I too had the stepping behavior on upward pitch wheel movements. I downloaded the zip file from the link in Ben's post, installed the new OS version, ran the calibration tool, rebooted, and ... pitch wheel is working normally !!! What a relief, thanks again - i'm very happy with my tiny brute!
I must say that it took quite a bit of digging (via internet search) to find this solution. And ironically it comes in the midst of a thread titled "Modulation Wheel." There are a couple of references to the "latest firmware version" but nowhere does it give the specific number (so i spent some time spinning my wheels with version 1.03.2, which is the latest available from the Resources page for the MicroBrute on the main Arturia website). Seems like there must be a better (more obvious) way to make this fix available; i bought my unit in August, so apparently there are still units in dealers' stock that have this same problem.
I will make the link known to Arturia Support (who knew about the calibration tool, but were silent as soon as i mentioned that the fix did not persist past reboots). Hope fully that will make it easier for others to find this great fix.
Once again many thanks to Bruno and Ben for persevering to make this new OS version 1.03.3 available to us all!