Post all of the number on your mower.
There are a lot of people on here who are trade so can verify them and verify warranty.
No idea on the USA situation but down here in OZ big retailers will buy heavily discounted remainders from overseas .
In this case the Australian distributor is not liable for warranty but the retailer is .
The retail chains try to con the customers into taking the mower to a mower shop but the mower shop can & will charge normal repair fees as the mower is not under an Australian distributors warranty
I get a few customers every year in this situation. Most times I can convince them to take it back to the retailer after getting a payment confirmation from the credit card company as proof of purchase if they have lost their receipt.
We had to disassemble and clean the carburetor on every XT engine we brought in, they were clogged with corrosion inhibitor. Some would not clean up and had to be replaced.