I have the EP-4 which is exactly the same but bears the Melco name. I asked my repair guy the same question a month ago and he did not know though he had had Janome training on the MB-4.
1000 hrs seems ridiculously low - that means even when used only one hour a day the motor should be replaced within 4 years.
I thought that also, but the message is on my screen every time I turn it on. The machine still works fine.
Does it ask you have you done it?
My Janome 500E tells me when the bobbin needs a clean and when I turn it back on it asks have I done it?
Maybe if so you could tell it a white lie and say yes and see if the message goes away.