Imo, if I had problems in the first 30 days, I would bring it back to the dealer for an exchange or refund and let them worry about the shop repair.
But I'm reading this correctly there isn't a dealer to take it "back" to; it was bought online? Dealers can have some justified hesitation to be quick to jump on repairs where people bought stuff online and now seek a dealer's help Some won't take it in at all, and others will work on them but naturally with a lower priority than for their own brands and regular customers. As stated splitters are pretty simple and easy to work on, so we rarely turn them away regardless of brand. The exception is usually due to the brand of the engine, not the splitter. Nearly any shop should be set up to service and often warranty Briggs, Kohler, and Honda engines. We'll turn away splitters with oddball motors because we're simply too busy to chase parts for this stuff. It's mostly a matter of it being impossible to accomodate everyone's need. It shouldn't necessarily be viewed as a "spite" thing.
Regardless of engine, the rest of the splitter must be warrantied by the manufacturer. Most dealers that will work on these units are probably NOT set up for warranty service on these brands, so it's up to the OEM to help the customer from the other end of that 800 number you are calling. A company may be happy to send you a pump or valve free of charge, but not every customer is happy, or capable, of doing the repair.
We did pretty good with the Ariens 22 ton splitter til they stopped making them. We can get Oregon splitters but they are essentially the same splitters that are down at TSC for $200-$300 less. We're sitting tight right now and actually recommending that folks run down and buy splitters from TSC. And if there's one of those rare 30 day problems that got through quality control, you still have a store you can take it back to. Not the case with shipping something back to an online seller.
But again I'll stress, whatever you buy, I strongly suggest you get something with a familiar name brand motor, not some random knockoff engine.