Tightening the spring on a DC arcade stick

[Vertigo]

Like so many other things in life, after a protracted period of breaking in and constant use, the spring in my DC arcade stick has become rather, shall we say, loose, so the shaft is far less responsive than it used to be.
It's in need of tightening.
Is there a way to do the proverbial "throw another stitch in for me, doctor" and solve this?
If so, how?
Cheers.

[NFG]

You can try removing and stretching the spring, though that's likely to prove temporary if it works.  You can try putting some washers between the spring and the caps, to pre-compress it a little.