syseng68k, the SS probably did not fail. The PF was able to achieve ND type inputs on several occasions. And if the PF pulled the stick and got NU he'd no doubt announce it and turn control over to the PNF whose stick would presumably work.
And I'd be tempted to look into "springs" and strain gauges. (The sticks gums cites very probably were based on strain gauges since they had so little movement.) Strain gauges have nothing to get dirty, noisy, or erratic. So they're a little more reliable.