'64 Omega is rattling..what could this be?

[vintagewaferthin]

Decided to wear my Omega cal 600 from '64 today since I haven't worn it in about 6 months. While holding it, I couldn't help but notice that it was making this audible, and quite loud(to me, at least) rattling sound. It was like a ting ting ting sound from the balance wheel that would go on and on, stop, and then start again. The watch has done this for a while even before today. ironic thing is, I had it "serviced"(I use that term loosely) in NYC in November of 2015. it had this sound before service and ever since i picked it back up. Obviously the "service" wasn't really done correctly, right? Whats causing this?