I just bought a 2602 Hammerdrill on 12-30-2011. Not sure if i posted in these forums about it, but I have the exact same problem. The day I bought it, I opened it in the truck before I left the store. Right away I saw the chuck wobble. I marched right back into the store and was going to return exchange it. As I got another unit, I opened it to inspect it before walking out...and I was amazed to see the same problem! A customer service rep and myself open a few more boxes and took it over to a demo display in the store to try out tools during the holiday season to test all these alongside other brands....all the 2602's we opened had a wobble!!!! I didn't have a true staight bit that I could use, but upon further studying in the store it did seem the outside collar/sleeve that loosens/tightens bits seems to have give it the illusion of a very out of wack chuck, but still the part that holds the bit still seemed out of trueness. I decided to hold onto it and take it home to inspect more. When I got home, I put a router centering bit in it and tried to see if it spun true...it still seemed off. I took a fostner bit and drilled a few holes with it. Though the hole seemed good, the bit seemed to spin with a wobble. I wrote Milwaukee on this and they responded :
The outside of the Chuck does not have a tolerance, but chucking a true arbor in the chuck and
Indicating the arbor about one inch from the Chuck should be less than .010
I have checked several Chucks from customers and none r/o more than .006
However; you may have a spindle or chuck issue and we offer a Fed Ex Label to ship to us for Warranty…
And one more thing on the 2602, the specs have changed quietly....torque down from 550 to 525 in lbs and rpm is up on low from 450 to 550. The 2611 specs of torque has also changed. Torque is up from 650 to 750 in lbs. Both versions are out there still. The only way I was able to tell the 2602's newer version, as they are bundled in so many ways, is to look at the specs on the box! I also called milwaukee on this, and the said they had changed suppliers for the gear mechanism. I suspect the reasoning of different suplier might be tied to the new M18 line "Fuel" coming out anyday now. You can see the specs at Milwaukeetools.com. On the 2602, its saing its a new tool, even though the 2602 has been out for quite a while, and the 2611, it looks like they just changed the specs. I'm sure other tool specs have changed, but i didn't bother to look. I may be just taking all the M18 stuff back I just purchased and waiting for all the new "Fuel" M18 line stuff.
****U P D A T E****
Today i called Milwaukee again. I asked both a customer service rep and a Milwaukee Tech both when we would hear more about the M18 "Fuel" line of cordless tools, BOTH to my surprise didn't even have a clue what the "Fuel" line was!!!!!! And with the Tech, I asked again about the wobble, if he saw a common prob with this model, he said "no". I also asked again about the spec change on the 2602 and 2611, he had no clue. I left it at that.
I went back to the store with my new version 2602 and rest of the M18 tools I just bought (impact driver and the one handed sawzall) in case I was going to return all of them, because without the drill as the core, I will go to another brand/system. Well they happened to have the 2602 with old specs and Red lithium battery (on sale as clearence, prob clearing getting ready for new fuel stuff). I took it out of the case, tested chuck, and it was soooooo much better. It did still have a tiny tiny wobble, but I figured I'd give it a chance. I did an exchange, and I will see how I feel about it in a few days. I believe Home depot gives you 90 days for returns, so if fuel line all sudden comes out, in next few weeks, I will return em again!