Last week I noticed my mower skipping and backfiring. Initially I changed out spark plugs. It was a Sunday so Land and Coats, the store I bought the mower from wasn't open so we had to cross reference the NGK BPR4ES spark plug to a Champion RN14YC. That didn't solve the problem so I dropped the mower off for warranty work since it is still under warranty. When I called to see if they had started on the mower they told me that they were finished and I could come pick it up but that they had to adjust the carburetor. However, since I had the wrong spark plug in the mower, the work would not be covered under warranty. The bill was $6 for new plugs and $75 to adjust the carburetor. I refused to pay the $75 because even though they changed out the plugs, the carburetor still needed adjusting which I feel should be under warranty not to mention the plugs in the mower were crossed referenced. Anyone out there have a similar experience?