4' is way too high...
A manual pump doesn't have an impeller, so you can just keep pumping till it primes, no matter how far it has to be pumped till it does. But electric macerator pumps use an impeller to pump waste...if the macerator is too far or too high, the impeller has to run dry so long that friction heat fries it before it can prime. That's why it's not working. And it prob'ly won't work after you move it till you replace the impeller. Electric macerators should be as close to the tank as possible, and ideally at or below the same level as the tank discharge fitting or y-valve. The higher it has be, the closer to the tank it has to be.
