Product review (5 stars): Front-load washer spins again!
For less than $20 and less than 20 minutes of work, my Frigidaire front loader (FTF530FS0) is up and spinning again.

I found a video on the internet where a kind-hearted appliance tech explained how to do the job.  The video also explains that if you can stop your washer in mid-cycle, and your machine lets you open the door right away, there is a good chance that you need one of these.

P.S.  Don't forget to check the filter basket for your pump motor, as a clogged one of those sometimes screws up the spin cycle as well.