Originally Posted by onyerleft

I had a new Shimano 9-speed chain that kept "catching air" as it moved up to connect the cogs, kind of like a chain will do when it's dirty and the links are funky. I cleaned and lubed the chain, to no avail. Then I ditched the master link, and re-attached the chain with the standard chain Park tool (blue plastic on the handle), taking care that the pin was nice and flush. Problem solved!

Needless to say, I remain suspicious of master links, although I'm not writing them off quite yet.