The problem you're having is caused by by binding in the liner. I know, this is a brand new machine but if you lead is coiled up or a hard angle right out of the machine, this will cause excessive binding on liner, thus resisting wire feeding through the roller.
THE CURE: when welding, make sure the cable/gun is as straight as posible, with no tight bends. this will ensure no tension is on wire when feeding through liner. this happens quite often on the smaller machines. I've got this machine and the 350P in the shop. The 350 has 4 grooved rollers, so the cable can be coiled up like a snake and still push through, but the smaller machines only have one, so weld with the machine as far away as possible so as to keep cable straight out of machine and i'll bet you have solved your problem
TIP: switch you gas to 90/10 instead of 75/25
THE CURE: when welding, make sure the cable/gun is as straight as posible, with no tight bends. this will ensure no tension is on wire when feeding through liner. this happens quite often on the smaller machines. I've got this machine and the 350P in the shop. The 350 has 4 grooved rollers, so the cable can be coiled up like a snake and still push through, but the smaller machines only have one, so weld with the machine as far away as possible so as to keep cable straight out of machine and i'll bet you have solved your problem
TIP: switch you gas to 90/10 instead of 75/25