Ike's tried to burn me on a warranty repair (Briggs-Stratton/MTD).."yes, we're a certified warranty center"... 2 days later ....
"no, it's looks like it might be ethanol related, so it's not covered under warranty (after accepting the mower and doing diagnosis)....estimated repair was $75 ($140 mower new)"
(Me)...."the manual says standard gas w/up to 10% ethanol is acceptable...give me my mower back"
(Them) "so sorry, please pay for our time and the NEW spark plug we installed" (mower still will not run).
(Me) "keep your new plug, give me my mower, you bill MTD for your time"...which is what finally happened (well, not sure on the MTD part...).
The only reason I did not initially try to repair it myself was the mower was 3 months old, looked like new....warranty work was justified. I dis-assembled the carb, found and removed some icky gummy gunk probably fuel related, re-assembled and it runs fine. Took me about thirty minutes, less time if it happens again.