Should I take my deck apart to fix a 1/2" lean?
Without pictures and maybe a diagram of some kind it's impossible to give you exact advice, so I'll give you more general. Decking is something you want to last for years, and if done right will add value to your home. Done wrong at the beginning it is likely to get worse over time, and could detract from your property later. 

It may be that you can fix the problems without that much effort, or it may be the only way to get it right is to take it apart completely, in which case that is what I'd do. 

I would also urge you to get some local help whether it is from a pro or an experienced amateur. Pictures are good but someone with a good eye who can actually see the situation would be better placed to give you advice then this forum.