This has been a common issue for many manufacturers over the past few years. The issue seems to be that certain water chemistries can affect the plastic of the jets, causing the retaining tabs to weaken or break. (search for BaquaSpa for more information) This is yet another reason why careful control of pH (acidity) and other water characteristics is important.
We have changed suppliers and now use a stronger material for our jets and jet bodies, along with new jet barrel designs that considerably reduce the frequency of this happening. We will not stop researching the situation until we reach the level of quality that our customers expect.
Jets that pop out repeatedly, or that have broken tabs, can be exchanged at your local dealer store. The exchange will be free if your hot tub is under warranty. This will improve jet retention, especially on spas built since 2004. The most recent replacement jets are called “Fixed Tab” jets (style and configuration may vary from your original jets)
Finally, you might try this service tip. It turned out not to be a final solution, but it might help.
If the jet is in the body, twist it firmly to the left then pull to remove it. Look in the hole where the jet was and locate the two screws that hold the black retaining ring. Using a Number 2 Phillips (crosshead) screwdriver, loosen each screw one full turn. The retaining ring will now have a little play in it. Replace the jet. Both locking flanges will engage the slot and the jet will be secure.
