Portable gas air compressor

I had a wheelbarrow type gas engine air compressor in my truck for years. Great for blowing out radiators and filling tires and nail guns for construction. As you can imagine, After several years in the weather, it looks really bad and mechanically began to fail, too. It was always in the way which was annoying.
I need on board air, but won't buy another gas compressor until I can keep it stored in a tool box.
My truck underbody boxes are 3x2x2. The only gas powered unit I can find that will fit in tool box is a Rolair GD4000PV5H. Very good quality compressors. Smaller pancake tank and Honda motor. Another nice thing: The pull cord it situated where if I drop the underbody box lid down, I can pull start it. It will live much longer in the shelter of a tool box/doghouse. If I want to take it out of the box, it's light and at a height that's easy to unload/load.
Problem is, this little compressor it really expensive for its size. Best price I can find is $749. Used units don't exist. However, I found a "new" one on EBay for $375 (shipping included). Seller claims they bought it, new in box, but it won't start. They say it has spark and that's about it. Seller has 100% reputation.
Any ideas what could be wrong with it?
Also wonder why the seller didn't return it to Rolair for warranty repair? (Asked them same, waiting on reply)
I'm in at $375, but thought I'd see what you, the experts, think about it.

https://www.ebay.com/p/Rolair-GD4000PV5H-4-5-Gallon-Pancake-Air-Compressor/2256270242?iid=264071991306&_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao%3D1%26asc%3D20131231084308%26meid%3D5fd561b4212d4021ad7712084dcc0bd4%26pid%3D100010%26rk%3D2%26rkt%3D4%26sd%3D323578282810%26itm%3D264071991306&_trksid=p2047675.c100010.m2109

Portable gas air compressor