Neptune MAH4000AWW Waher will fill and empty but the drum will not move in any cycle.

If the noise starts before the drum starts to turn it might be the pump is obstructed. If it starts soon as the drum starts to turn then might be the drum bearing. If it is a knocking vibrating sound open the door and grasp inner drum try moving up and down and side to side . If there is any movement aside from the whole mechanism then the spider that holds the shaft to the drum is broken . Need a tech

Check pump / outlet filter , refer to instruction book , clean and replace then re- try

Does it fill when the machine is powered down?

If it does then the fill valve is stuck open and needs replacing

If it does not then you need to check the pressure switch and the air bell on the outer drum which probably has a ball of jellyfied soap in it.

If you take the back off you will see a thin plastic or rubber hose going from the bottom of the drum to a small flying saucer type object.

If you pull the hose off the bottom connection and blow into it you should hear a clicking noise from the pressure switch.

If it clicks then clean out the air bell and refit the hose .

If it does not click then get a new pressure switch

A repairman would test it live but that is not recommended for untrained people

BELT IS LOOSING TENSION CAUSING IT TO SMOKE REPLACE BELT

Drum size or capacity for the Neptune Model Number MAH4000AWW is 3.4

its your pump.get at it thru the back.it may be blocked or may have failed.a volt meter will tell you if its getting voltage.if so should drain,make sure on about spin setting to check.ive had to replace the pump on my neptune

Drum capaicty is 3.34 for the Neptune Model # MAH4000AWW

The repairs it called for was way over my head so I took it to a repairman today! Thanks anyway

Try some WD40 on the door lock.

Check for low water pressure. Clear screens in inlet valve. Do-not remove screens. This unit will turn off if not filled in specified time.