Product review (4 stars): EUREKA! I got 'er done.
EUREKA! I found the problem.

As many have stated here the Whirlpool Kenmore and God knows what other rebadge have a problem.

I was ready to replace yet another, 3rd to be precise, rack adjuster, when I started studying the
whole contraption and noted that the adjusters are NOT IN THE MIDDLE. Instead, they lay at the border
between the mid and rear third of the tray, so they can make room for the glass stem holder on one side.
Of course there will tremendous force on the wheel hubs as the closed rail now acts as a lever, remember Archimedes?

So I threw the glass stem holder in the trash and transplanted both adjusters to the middle. They love it over
there, the whole tray has been sliding with great ease now for 3 months, fingers crossed.

Sorry for delay, I wanted to make sure it worked.

My next idea will be to install total of 4 roller assemblies, that is if it breaks down again.