Putting all belts on

Here's the owners manual which includes belt replacement.

http://www.hammerwall.com/Download_Manual/38636


Here's Sears parts direct, with 11 diagrams of the mower.

Model zts7500 CRAFTSMAN REAR ENGINE MOWER Parts

Hello ron... that model uses tractor drive belt part number 144959 You can order it directly from Sears at this link

http://www.searspartsdirect.com/partsdirect/part-number/Craftsman-Parts/Riding-mower-tractor-Parts/144959/0071/917/Model-917272440/0247/1509200?keySuffixId=NA&productTypeId=x&searchModelNumber=917272440&subCompDesc=Mower%20deck&brandDesc=CRAFTSMAN&modelDesc=LAWN-TRACTOR&pathTaken=partSearch&blt=11

Joe

Sears has one convenient location on the web to get all your Craftsman parts. They carry most parts for you tractor for at least 20 years.
You can get a new belt from searspartsdirect.com. You will need the model number off the mower to find and order the part. The number looks like 917.123456.
When you enter the model number into the search box at searsparts diagrams will pop up. You can locate the belts and order right there.

If you can't figure out the diagrams, you can go to any Sears store and they will help you order the part. All Craftsman parts are plus shipping.
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OLDER SEARS TRACTOR WILL NOT SHUT OFF WITH KEY. STARTS FINE.. ANY IDEAS WHAT TO LOOK FOR?

On page 10 and 11 of your owners manual it shows how to connect the belt to the trolley. You should be able to reverse these instructions.

Replace your solenoid.

There is no tension adjustment it has an idler pulley working off from a spring. Check to make sure that the spring did not come off or break. If neither of these have happened then the belt is stretched and you need to purchase a new one.

Here is a picture to help you place it on right. There are two deck designs pick yours.

have you tried www.searspartsdirect.com

you might check the pulleys to see if shear pin has broken.