I use Wix filters on my machines. You can do a search on Google to find where to buy them. Or, just go to any NAPA store, their filters are made by Wix. Wix filters are one of the highest rated filters made. Do a little search on Google and you'll see what I mean. My second choice would be Purolator filters.
Kreiling's Lawn & Landscape Service
Spring Hill, FL (West Central FL)