How do I fix my deadlift form?

[ayjay23]

So I've been noticing that there's a little roundedness on my lumbar. I thought at first because I was going heavy, but then I tried lightening the load and it appears that I still have it. >.<

I also consciously tried to push my chest out and forced myself to have a lumbar arch, but they still wouldn't work. >.<

Below are the the videos (heavy and light versions). I'm hoping that some of you might know what's going on. Thanks.

Heavy:
http://www.youtube.com/watch?v=Wp0ug2BZI2c


Light:
http://www.youtube.com/watch?v=ws0HyqQ564k

[elVarouza]

I watched the heavy video. It looks like you can tighten your back fine, but your shoulders are way too far in front of the bar. You actually need to drop your hips a little and pull your chest up more.

[ayjay23]

Thanks, elVarouza.