I've had this stick for decades and never really liked it because the lever was sticky. It had a tendency to not return to centre, making it borderline unusable.
While taking some pics of its guts recently, I pulled out the metal washer (shown below), and realized that it was fairly cheaply made, with a sharp ridge on one side but not the other.
Dreamcast-Stick-Fix-1.jpg
That ridge is what prevented it from returning to centre properly.
So I flipped it over, putting the sharp friction grabby side against the base, allowing the lever to slide across it smoothly.
Problem solved, and such a stupid, simple fix.