I'm sure most of us have experienced a shroud dropping out while raising the mast. Keith of hull 1124 saved me this frustration by sharing his idea of using a short piece of Nite Ize gear tie. You need around a 5" to 6" piece cut from the stock length. Just stick one end in each of the side shroud holed after inserting the T-ball connector. They seem to have a core then does not corrode and don't fall out while sailing.
Gear Tie® Reusable Rubber Twist Tie™ (niteize.com)
A trick used by several California Weta skippers is to use foam earplugs pushed into the mast opening after installing the T-ball connector. Simple, reusable, dirt cheap and ubiquitous, it works very well.
The Weta stock stainless steel shrouds stay in the mast. However, if you have synthetic shrouds, they will drop out while raising the mast. We put electrical tape at the top of all 3 around the mast before raising. Does the trick!