Look at this Mig dot.
http://s5.photobucket.com/user/rmccartney/media/Metalworking/Picture105-1.jpg.htmlNo heat added, it was planished cold, and no cracks. Despite all the hoopla online about Mig welds cracking, I've never seen it first hand.
At this point, given no access for planishing, I would leave well enough alone, grind down the weld, and use some filler to repair the low.. If you can't get a dolly in there, you're done with the hammer.
