Frigidaire Affinity ATF7000E Front Load

First, get a level and see how even it sits upon its surface. If it is un-level, just level it out. You can accomplish this by adjusting the feet under the bottom of the machine {one per corner} until the bubble in the level is centered at all four points of the washer.

Remember, righty tighty, lefty loosy.

If this does not solve your problem, try loading the washer as evenly as possible.

The belts wouldn't cause shaking, next forget about the bearing if it was bad you would have water leaking from the agitator.

Start with the easy stuff I suggest running a full cycle with the machine empty. If the shaking stops, then your loading it unevenly. However if it does not help the problem then first check the foot pegs under the machine adjust them until the machine is level, if that does not help.

Then the problem in internal, first check the mounting brackets for the motor anything loose/broken, if so tighten/replace brackets. If everything is ok then you have to remove the top panel of the machine.

There is the tub that spins on the bearing the " the active tub"(the one the clothes go in obviously) and around that tub is the "stationary tub", between the two are what they call "snubs" these are either rubber wheels, bushings or on cheaper models just a rubber boot that works as a shock absorber if you will, and keeps the movement of the the "active tub" with in its axis. If a wheel is broken, or a bushing/boot is torn or broken then there lies your problem.

I hope this helps.