Bought a used Canon Pro-10s - Do I try and return this or is it still salvageable/fixable?

[The Hat]

makes a very high-pitched noise when its turned on at its power button so keeping it on isnt ideal. Thanks

Yes the printer likes to be left plugged into the power socket when not in use, and you can use auto power off setting to suit your needs, plus quite mode that cuts down on the noise levels when in use.. Tip try covering it with a cloth or plastic bag when not in use, that helps keep it clean and makes it disappear..
click to enlarge..

 

[palombian]

Any other little issues will soon be ironed out once a few prints are done and proper ink starts flowing once again.. Remember the original users ink was all crap..

Agree, the ink in the printhead will dissolve the last impurities.
Do a few nozzle checks every day.

Enjoy your printer and take care of it, you won't find anything better to refill.