Booties.
Post a picture of the jet after it's popped out, lets see if we can identify it.
I'm particularly interested in the rear part.
Are yours threaded or clipped in.
If they are threaded, what's the state of the threads ?
Jets go brittle with age and chemicals, if they are threaded, then it may be that the jet body has also gone.
If they are clipped, then in all probability, only the clips have gone with age.
I believe there are a number of very common jets which most manufacturers use.
(Why redesign something which already exists and is readily available ??)
It may be possible to purchase the diffuser (rear clip in/screw in section)
I fixed mine for less than £4.00 each.
Search Ebay for words like Waterway poly storm, power storm, maxi storm, mini storm, cluster storm.
Without seeing your exact jet it's difficult to say exactly which one you require, but it's a start.
