"Run" is correct. "Go/run like clockwork" is an idiom, it's mean to happen without difficulties or problems.
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.
tamguatlayDon't you wish that all transport systems run like clockwork.I would use "ran" in this particular sentence.
Cool BreezeThis may be to some extent a matter of personal preferenceHi, CB.