Question about my Fightstick

[LEFT]I let my older brother use my Madcatz TE S Edition stick over the Christmas holidays and he really put a number on it.[/LEFT]
[LEFT]Moving the stick to any position except for up+left feels loose. The stick doesn’t jump back to the neutral position as good as it did a couple of weeks ago.[/LEFT]
[LEFT]Anyone with experience know what piece needs to be adjusted or replaced?[/LEFT]

Sounds like the centering spring inside the actuator shaft on the Sanwa JLF stick has spazzed out. You should be able to get a replacement one here:

When you get it, you need to unscrew the back panel of the TE stick to get access to the bottom of the JLF stick, use a flat tip screwdriver to pry off the e-clip holding the actuator (black rod on the main shaft), replace the faulty spring in the actuator with the new one and slide the actuator back on securing with the e-clip.

Thank you very much DeadAgainKen. I will definitely take your advice and take a look at the spring.

Update: It was the spring. Opened the top of my TE S stick, took the spring out, stretched it out, put it back in, now its good as new.