Im buying my first used engine driven welder and am a little nervous so hoping the membership can provide me with some tips

The machine is a 1999 Lincoln 300 classic. Runs on gas. 5600hr and recently serviced. Guy wants 3500$ CAN firm.

I tested it out by burning a few rods throughout the different ranges and made some nice beads. It idles nice. Didn't think the arc struck that easy but that might just be me.

I'm planning on buying it tomorrow but after having told the guy, I'm a little nervous. I don't feel like running a few stringers is an adequate test run. And I'm not sure what to watch out for in a bad machine.

Apologies for coming to a blue welding forum to ask about a red welder but this is the only place I know. Any tips will be much appreciated.