Re: What would you do? PLEASE REPLY
You put "brand new" in quotes. Was the unit new, refurbished, or slightly used? Since this is a unit that has a reputation for reliability, it could just be a new engine not assembled properly or if "slightly used" might have been damaged before being returned.
The answer will actually will be pretty boring: What does your warranty cover? If you're covered they'll take care of you.
If I were you I'd document what has happened so far, call your DISTRIBUTOR about your concerns for the future health of this engine and see what they have to say. Document that as well. Unless this was not an authorized HM distributor, the distributor that sold you the unit is the one with the responsibility to take care of the problem, and if they can't find or fix it, it is their responsibility to work with the manufacturer to find a solution. They have more clout than you do if the manufacturer balks. "We only sell them" is a line that I'm sure would anger any manufacturer if they heard a distributor using it. They don't get to run away when there's a problem make you figure it out.
If they aren't an authorized distributor of that brand of machine, you might be on your own.
Only when you can't get satisfaction from the distributor do you go directly to the manufacturer. Be calm, send them your documentation and ask them where they will go from here. Be reasonable and they'll likely go overboard to find a solution.
PS: I am not a lawyer nor do I have much experience with leasing, but as a last resort you may want to check your lease to see if excessive downtime is a reason to break the lease and return the unit.