Ehhh, hard to say. It has the single cyl. Courage in it, which develops valve cover leaks, the top crank case bolts can work loose, wack your flywheel and crack your block.
Check that the spindle bearings are good, just rotate the blades by hand (be careful) and Check for roughness or binding, spindles, OEM ones are about $70 new, each.
I'd say 500 hours might be about half of The engines life, maybe less
Depends on how well it was cared for.