Hiya Chris! I'm no doc (hey, neither are you -- see our disclaimers!

) but my humble opinion is that so long as you don't have pain and you have a full range of motion (and your doc's OK), go ahead and work tri's. BTW, that flabby arm Jello stuff is also known as "Bingo Arms" here in Western PA

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I'm guessing that your nose breakers are what we call skull crushers (there's lots of other names) and I think they're the toughest of all triceps exercises, so no wonder your poor elbow was cracking. My knees pop and crack like that on squats and lunges and a doctor told me that's called "crepidation" -- like in decrepit, get it?

Like old and falling to pieces? She said that there's nothing wrong with the noise so long as there's no pain involved. So I keep snap, cracking, and popping on Leg Day with no apparent harm.
Perhaps you could back off on your nose breakers for a while and try a triceps machine, pushdowns (with a rope or bar), or kickbacks with light DBs until you get your strength back to where it was before you broke the elbow. You're already doing the overhead extensions, right? There's also close grip bench press with a bar or Smith machine or good old pushups with your two hands in a triangle. I think the key is to go light until you build up a little more strength and then go back to the lying extensions. But don't be surprised if your elbow keeps making noise.
BTW, I hope you have a good spotter on those! I'm always antsy when I do them since I dropped the bar on my forehead once when my spotter wasn't paying quite enough attention -- ow ow ow -- one of my many bruises.