Usually a cylinder latch problem is the result of a faulty latch spring. It's a tiny little spring installed under the latch (it's what makes the latch move back and forth, but that's pretty obvious).
Like YNH said, it's at your own risk whenever you take a six-gun apart. Sometimes putting them back together is near impossible without visual instruction or a smith's assistance. Also, depending on if the latch spring needs to be replaced or not, some revolvers have a simple spring that's easily replaceable while others have this weird flattened spring that's a pain and a half to aquire (or at least aquire cheaply). I'm pretty sure that those are only in large frame Colt revolvers though (from my experience at least) so hopefully you won't run into one.
If you're bringing it to a gunsmith though, they should be able to fix it fine. Just hope you don't need a flat spring replaced. That will be an extra hassle you don't want.
__________________
|