Product review (5 stars): Replacing this part fixed my spin problem and numerous error conditions
I have a Whirlpool Cabrio belt-drive washer, model WTW5640EW0. It was failing during the spin cycle, sometimes with a blinking lid lock light.  Sometimes the machine would repeat the rinse cycle wasting vast amounts of water.  Error codes indicated (among other things) basket speed sensor fault, over suds, motor RPM, and unbalanced load.  My first attempt was to replace the suspension rods.  It was easy enough to find the part (on another website).  Installation was easy.  New suspension rods helped, but the spin problem was only slightly improved.  Replacing the actuator fixed EVERYTHING.  The machine runs like new.

See Youtube for helpful videos on disassembling your machine.  There are also videos that describe using the machine's diagnostic mode to see error codes and run self-tests.  Use Google to find the appropriate tech sheet for your washer; it will describe the error codes and test modes.

This part is a 10 minute fix; very easy to do -- but only if you know how to run the calibration cycle (see the tech sheet).  For the cost of the part, it's a better use of time and money to replace it on speculation if you have spin problems.

Also recommended is the W10315818 cam kit.  The washer has a pulley and a nylon splutch, both with teeth that will grind down over time.  The cam kit replaces the pulley, the splutch, and a spring.  This part (actuator) moves the cam, working against the spring, to activate the splutch.  I plan to replace the pulley/splutch assembly as soon as the kit shows up.  I noticed that the spring on my machine was not very strong; I stretched it a bit to provide more force to help engage the splutch.  It will be sufficient until I can replace it.

People have told me that the Cabrios have all sorts of problems, many of which are not worth fixing.  I am willing to go as far as the suspension, actuator, and splutch assembly, but that's about it.  These parts are easy to install and reasonably priced.  If the machine needs anything more than this, I will probably junk it.

Rated 5 stars because it's the right product for my washing machine, installation is easy, and the machine runs as good as new.  According to my online research (and my own experience), this is a failure-prone part.  I don't expect it to last more than a year or so.  On the basis of quality and reliability, this is probably a 2-star part for a 1-star washing machine.