What maintenance tips should I know before buying a screw pump?

I learned the hard way that buying a screw pump is not just about checking flow rate and price. A few months back one of our machines started making this ugly grinding noise and everybody thought the whole thing was done for. Turns out the previous owner barely changed the oil and never checked the seals. The repair bill was painful honestly.

So before getting another one I started digging through forums and supplier listings late at night trying to understand what actually matters for maintenance. One thing I kept seeing was people saying to check how easy it is to replace stators and rotors because some pumps become a nightmare once they wear out. Also learned you gotta ask about spare part availability first instead of after the breakdown happens.

I was browsing through Alibaba listings too and weirdly the reviews and photos helped more than I expected. Some sellers actually showed maintenance videos and teardown pics which made things feel less sketchy.

Now I am stuck between going for a cheaper model or spending extra for one with easier servicing. Anyone here been through this and got suggestions?