Small Engine Troubleshooting Problems? Ask a Mechanic Now.
HI, my name is***** will be assisting you.
With a new drive belt I wouldn't think that you would have this type of problem but a couple of other things do come to mind as I was reading about your issue.
Based on your reply to my comment then I would suggest that the hydrostat transmission is bypassing internally due to faulty swash plate surface or seals inside the transmission and will either need to be rebuilt or replaced.
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