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How to adjust drive belt on 6.75 Horsepower self propelled lawn mower, Model # 917378420

My walk behind lawn mower drive belt slips when it is under load during the mowing process. Just had a new transmission installed in the last week. Would like to know how to adjust the drive belt.

Lawn Mowers
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2 Answers from these members:
Joseph Perez
I know how important it is to have a good working mower in the home so that you can keep your grass nice and trimmed. While you are waiting for your expert answer, I did manage to find a link that will provide you with some good information to help you with your question. I hope my link is useful.
by Joseph Perez Earned 14,951 community points in Lawn Mowers
September 3rd, 2011
Answered in 9 minutes
0 votes
Mark T
Thank you for your question.

I am sorry you are having a problem with the mower. I have looked up the model number you have submitted. There is not a belt adjustment on this mower. There is a spring on the transmission that keeps the belt tight. To check the spring you will need to remove the belt cover on the front of the mower. Then look for the spring that connects to the transmission and the mower housing. If the spring is connected, leave the cover off and start the mower. Then engage the drive once it starts slipping look at the pulley on the transmission. If it is not turning, the belt is slipping. If the belt is old, I recommend replacing it first. While installing the belt you can scuff up the v part of the pulley with sand paper. You will also want to clean any oil that is on the pulleys. Oil will cause the new belt to slip.

I hope this is helpful.

Please let me know if you need further assistance on the repair of the mower.

Here is a link to order any parts you need.

Sears Parts Direct


If you do not feel confident repairing this problem yourself, then you can have it repaired by a Sears technician. Here is a link that will provide the nearest drop-off locations:

Sears Home Services


Thank you for using Manage my life.

by Mark T Earned 54,715 community points in Lawn Mowers
September 6th, 2011
0 votes
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