how longs does the spherical bearings last...?

[Gilles]

I had the Tarett sway bar links and also the Rennline F/R toe links on my 987CS for a few years (maybe 10-15k miles..?) and thereafter I installed them on the 981CS.

A few months ago I noticed a faint rattling on the rear axle (my wife complains that it sounds like an old car..), got the car on ramps and started poking with a rubber mallet and when I tap on the driver side toe link I am able to replicate the rattling, checked and all the bolts are tight therefore the spherical bearings may be on their way out.

Do you believe that the spherical (Aurora..?) bearings are dead and need to be replaced? How long are these usually last?

PS: This is my first time using adjustable links therefore I don't have much experience with their life span..