Welder problems

I just bought a little lincoln welder from home depot to do a little sheet metal work with. I get everything hooked up, but the damn drive roll spins backwars when you pull the gun trigger. What is causing this? This isnt allowing the wire to feed into the gun cable. Please help so I dont have to haul this damn thing back to the store. I just bought it today!

Check for a switch.. there should be one on the inside of the casing.. should change wire directiong.

u might try switching trigger wires i cant remember if that makes a diff oor not