Thank you for your question.
I am sorry you are having a problem with the tractor. Usually when the deck hits the rear tire it is because the deck adjustment. If the front of the deck is too low, the back of the deck will hit. I have added an image below that shows how to adjust the deck. If the deck still hits the rear wheels, I suspect the problem is worn deck mounts.
As for the mower stopping when in tall grass I suspect the problem is either a worn belt or the idler arm is binding. First, remove the deck from the tractor. Then move the idler back and forth to make sure it is free. If it seems tight, you can soak the pivot with WD-40. Once you have confirmed the idler is free check the condition of the belt. If it looks worn, go ahead and replace it. Here is a link to order any parts you need.
Sears Parts Direct
Please let me know if you need further assistance, on the repair of the tractor.
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
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