About 5 years ago I installed 8 sets of the Knape & Vogt GS4270 full extension, soft close drawer slides.

One set, the one on the most frequently used drawer, no longer fully closes on its own. When I give the drawer its normal push, it glides to about 1/2" from fully closed and then stops. The soft close mechanism does engage, it just doesn't pull the drawer all the way closed. A gentle push gets it closed, but it's a "manual close" i.e. I don't feel the mechanism taking over..

I can "fix" the soft close issue by fully extending the drawer (the standard full extension reset method) but this only solves the soft close issue for a day or two, probably some X number of usages.

I called KV tech support and other than "make sure all the screws are tight" and "make sure nothing has shifted inside the cabinet", he had no other suggestions. When I asked about lubrication, he was pretty emphatic about not trying that.

Unless someone has a suggestion, I think replacement may be my only option.