If your mower wheels are locked, is making a popping / clicking noise or sounds like it is binding when it runs, not running as quiet as it once did , the chain is worn/stretched beyond it's service limit and ready to fail. Order replacements now to have on hand for the inevitable.
Please measure and verify the actual # of links or the overall length of your drive chain before ordering.
If the chain you need is longer or shorter, contact us, we will make one especially for your needs.