Did you moved the little springs underneath? No I didn't, but could in fact increase a bit the stiffness... Also, you could take off all the greace (not sure bout that english word), and reapply greace... it's somewhat 'sticky' at original state. Loose is good, mine recenters very slightly in fact, but I like it now
Play a couple of hours with the spring then, or without... you'll figure out later on what's best for you.
Sound like something is very very wrong. My warthog is extremely precise, with 0 deadzone. The first hint of movement on the stick (a few mm of physical deflection) will register movement. Perhaps try checking your joystick settings / calibration in windows control panel?
I didn't eve know there was a control panel in windows for that. I am a mac user and using E : D on bootcamp, so not used to the intricacies with Win....anymore.