M,
Are you saying the inner dimension of the insert is touching the crystal/retainer and popping out the insert?
I'm thinking if you can get the insert to snap into the bezel...while the bezel is off the watch...but then installing the bezel/insert...the insert pops out...might be a different problem. Many have had issues gettin inserts mounted because really tight fit, but thats different than your problem.
To be sure, you know for fact you have a 16610 insert and not a 14060 or 16660?
The latter two are different sizes inner diameter.
Oh...and congrats!