A lot of hardware/software issues with Bitmain S3 and S3+ miners since launch.
Again S4 have PSU issues.
But you mentioned in your rating as minor issues only.
Please revise it if possible.
Nothing wrong with S3s, they're probably the most prolific single SKU of any miner outside of USBs.
They're considered minor issues as customers are being compensated - only the company losses out.