This is a month old so the OP figured it out or smashed the welder .
Rule of thumb!!
The drive tension should be set to slip (drive rolls spin) with a pinch of the wire between thumb and index finger .
Then how one holds the gun while welding plays in
Always in a straight as possible line which means sometimes much moving around of the welding machine
Another problem area is bending of the front of the gun where the cable enters the plastic .
If the tension is to tight it will cause a bird nest
This will also could cause the wire to burn back again causing a bird nest.
The bird nest most often are caused by the wire being stopped in front of the drive rolls with tension set to tight.