The model number that you have submitted was not a complete model number. I have provided you with the charging system information out of the service manual for a model I think is similar to yours. The image has trouble shooting information also. You can get a tractor-wiring diagram from this link.
. This information is intended to aid in the repair of the tractor. If you do not have the knowledge of using a meter and safely make the checks, please call a service tech. If you need further assistance, please resubmit your question with a complete tractor model number.
Working with live electrical current can be very hazardous and possibly deadly. Testing voltage output requires working with electrical current. Do not attempt this measurement without the proper tools and safeguards.
Here is a link to buy the parts needed from our parts web site
Sears Parts Direct
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