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I am sorry you are having problems with your washer.
The F21 and the F33 errors indicate drain issues. The Sd is most often associated with too much detergent being used.
I recommend ohming the drain pump from the main control board before you replace it. It should ohm at about 12 ohms down the wires. You should make sure the wire harness connection at the main control is good. Check the pressure hose connection at the pressure switch and at the tub. I also recommend making sure the washer is not full of suds.
To gain access to the main control you will need to remove the top of the washer. There are screws located along the top rear edge of the washer top that will need to be removed. I am including a wiring diagram below.
If you do not feel confident repairing this problem yourself, then you can have it repaired at your home by a Sears technician. Here is a link for the website:
Sears Home Services
Here is a link that you may use to view the parts list diagram and for parts purchases;
Sears Parts Direct
I hope this is helpful. Check the things I have covered here and if I may be of further assistance as more details become available, please reply to this post.
Thanks again for using Manage My Life.