Check the key on the drive coupling. It could be missing and there is just enough friction to spin the pump with no load.
When I bought my County Line splitter at TSC a few years ago I asked it ( person selling to me) if oil and hydraulic fluid were full. It said they were. I took it home and decided I should check fluid levels myself. Oil was fine but hydraulic fluid was way low. I went to the hardware store and bought 2 gallons of fluid, which cost about $50 if I remember correctly. It needed 1 plus gallons of fluid. I contacted TSC stating my displeasure. After a bunch of arguing they agreed to send me a TSC gift card for $50 and thought everything was peachy. I said "Fine but I will never shop at TSC again. You have covered my expense but not my time and trouble." The lady had to check with managers about 2 levels up to get approval to give me a $100 gift card. I thanked her, spent the card online, and no longer shop at TSC.
Hopefully they take care of it for you...most of the time they just swap it out for another one. If they are willing to do that, tell them you know someone that would be willing to buy it as is...well, as long as they are reasonable about it...
They were sold out of that model. I'm not happy about it. I'm only home two weeks and I had a large silver maple and large oak both cut down. They were both dying and close to house. Had them leave the wood now I don't have a splitter to processs probably three cord between them.