Weird, their website says the entire unit needs to be sent. Who is barbara and how did you get her contact info?
https://shop.bitmain.com/workOrderGuide.htmb. For the miner, if your miner is:
S9: Ship the whole machine
T9: Ship the whole machine
R4: Ship the whole machine
L3+: Ship ONLY the defective part or the whole machine
D3: Ship ONLY the defective part or the whole machineS7: Ship ONLY the defective part, please do NOT ship the whole machine
Turn the voltage of missing chain from 3-6 , it may appear . Look like lowest voltage & 1, 2 only work well with 220v D3
All D3 is 12 volts.