Hi,
Have a look at the leaking jet & decide whether it has a screw thread & a nut fitting in place or if it's bonded to the tub.?
If it's held on by a nut, a new gasket will probably suffice.
If it's bonded on, it will need to be very carefully removed.
The mating faces THOROUGHLY cleaned-up & the exactly right kind of adhesive used, to re-bond the jet onto the tub.
Then it needs to be left to properly dry & cure, before you put any water in it.
Best of luck
Yes, I replaced mine from the top. It's fairly easy. You have to pop it out after you get the trim off carefully and then pull the air switch out remembering to get the 1/4 house to come out with the air switch so you can detach it and connect the new one.
Cheap plastic fatigues with heat . Silicone will work but will not keep the crack from continuing. The fix depends upon what type of plastic you have . It is likely a polyester like fiberglass in which case you can use regular fiberglass to fixit . Rough up the outside with 80 grit , brush in fiberglass resin ( don't forget to mix in hardener) lay in glass material , repeat until built up . Repair the front with a good "gelcoat " repair kit which allows you to mix match color.. sand with 220 , then 600, then 800, then 1500, then 3000 , polish with automotive whit polishing compound , wax
