If Jett requires an infinite FMA to be somewhat playable, perhaps it's time for a technical intervention. Imagine yourself a designer and you are tasked with giving Jett a skill overhaul. Now, keep an open mind and ask the following:
What trait/gimmick/quirk/skill does Jett currently have which sets them apart from other MS classes?
How kind of a unique playstyle can be build around that particular trait?
What supplemental skills are needed to make this playstyle engaging, challenging, and fun?