I replaced the hatswitch once on my old Cougar joystick. That was fairly easy, though I foolishly didn't set up my work area properly, and the hatswitch fell off my work surface onto the concrete floor and the hat broke. So I had to order a second one.
You don't mention what model of Thrustmaster throttle - is it a Cougar, or Warthog, or what? There may be forums out there that can help you. For example, the Cougar has Cougar World at
cougar.flyfoxy.com.
My advice is to order the part, try to find instructions on a user website, and try it yourself carefully. If you feel like its beyond you, take it to a shop then and have them do it.
