That really helps. Now I know which file to edit to add that extra option. Unfortunately, it didn't help.
What does "--bet-clk 20" do? I don't think I've seen that command before.
As far as you thinking that your USB adapter is broke, do you get the same results as I do when I run the following below? It's like you said, cgminer detects it, but like you, when I look in Minera, it says "No local devices found". I've used 2 different USB adapters with the same results
minera@minera /var/www/minera/minera-bin $ cgminer -n
[2015-12-09 22:36:51.130] USB all: found 4 devices - listing known devices
.USB dev 0: Bus 1 Device 4 ID: 10c4:ea60
Manufacturer: 'Silicon Labs'
Product: 'CP2102 USB to UART Bridge Controller'
[2015-12-09 22:36:51.133] 1 known USB devices
Does your boot log show anything useful?
minera@minera /var/www/minera/minera-bin $ dmesg
I get a whole bunch of this.
[ 4114.924623] cp210x 1-1.2:1.0: cp210x converter detected
[ 4114.929049] usb 1-1.2: cp210x converter now attached to ttyUSB0
[ 4121.220096] cp210x ttyUSB0: cp210x converter now disconnected from ttyUSB0
Did you ever get Minera working?