Here are your parts
Replacement parts for FRIGIDAIRE FLXE52RBS9 Laundry Center - Frigidaire | AppliancePartsPros.com

Here is a wiring diagram which may come in handy in the future
http://manuals.frigidaire.com/prodinfo_pdf/Webster/131988900.pdf

And a manual which should be close to your unit
http://frigidaireservicetips.com/pdfs/488_3.pdf

Run your fingers around the seals at the front and back of the drum just in case something has jammed in there. Be careful, it may be sharp.

If clear
You will have to open it up to find what is causing the problem.
Odds are it is the rear bearing but may also be the front glides etc..

Be sure to re-lube the rear bearing using hi-temp grease.
Since it is a pain to work on I would replace anything that looks worn.
Be careful when removing the rear grounding ball bearing (Item 5 in Section 1). Once released it likes to take off and play hide and seek.
While in there check the belt etc.
Give the interior a good cleaning including a clean/check of the blower.
Turn the motor manually to ensure it's bearings are OK.
Also a good time to clean/check your vent system.

Note: There is a possibility that the motor will have to be replaced but you will not know this till you have the drum rotating manually.