Welding question

[John Pasinski]

I'm trying to repair the cab inner fenders on my '72. Like most others', mine are torn, and the one on the right side is missing the section that formerly was positioned under the battery box. Here's the dilemma: These fenders just WILL NOT accept the weld! No matter what settings I use (setting "A" wire speed 2 1/2, too weak, setting "B" wire speed 3-4, burn through). I have a Lincoln 3200 (from Home Depot). I'm using .025 steel wire with argon/CO2 gas. I have double checked the polarity (it's correct). I have changed the gas pressure from 15, up to 40#. I'm getting gas as I can hear it when I pull the trigger. I have cleaned, and reconnected the ground cable and clamp. I have cleaned (using a grinder and disc sander) the fender to shiney metal at the grounding connection, and as best I can at the welding points. Any attempts, and the arc is "weak" and comes out like looking like I used no gas at all. It looks like bee bees, or bumpy and blotchy (is that a real word?). So I suspected the welder itself. I've used this welder for 5 years now. So I happened to need to weld a unit number on a handle to another machine. Perfect time to test the welder itself. Well it welded perfectly! Conclusion; the welder is working fine. Yeah....I could buy new fenders, but jeepers, they want so much just to ship the things (LMC $225.00 each). Beside that, just for my own self respect I can't let this thing beat me! Any suggestions from anyone? I sure will appreciate them. Thanks.