Samsung washer WF42H5000AW failure

[TCHeywood]

My WF42H5000AW front-loader (15 months old) just failed in such a way that it can't properly spin. Per the Technical Information sheet from Samsung, I performed the troubleshooting steps including the Quick Spin Test (after emptying and draining the unit, and verifying the filter was clear, etc.). The unit does not successfully spin in the Quick Spin Test - when it tries to spin, it shudders a few times and maybe rotates about 30 degrees of rotation in 5 or 6 jerking movements before it stops (presumably sensing it failed). However, no error codes are generated/displayed.

I verified the motor winding resistances on connector CN6 were correct (approx 12 ohms between pins 1/2, 1/3, and 2/3), so the troubleshooting guide indicates the action is "change PCB". 

So I'm inclined to order parts, but it's not clear whether the PCB to change is the Inverter PCB (part #10 in the Samsung diagram - and what the CN6 motor connector is plugged into) or the main control PCB. I'd rather not have to buy both and send one back. Has anybody had experience with this type of failure and if so, what did you replace to fix?

Thanks much,

Tim Heywood