Maytag Neptune front load washer, model MAH8700AWW, 4-5 years old. At ant low or high speed spin cycle, the drum bangs badly regardless of load size. Why & what can be done to fix this?

Replace all four struts

In some cases it is a simple adjustment of the Levelers. Use a flat level device to check the levels from front to back and side to side. Make certain the Washer and Dryer have a space between them and they do not bang into one another.

Something is causing the drum to be way out of balance. Does it bang and make noise when it's spinning empty? Probably not. Is something stuck on the side (inside of course) of the drum, causing it to shake when spinning? If not, a spring or shock absorber (connecting drum to sides, bottom or top of machine) has broken or come loose.

you may need to put some anti vibration shock pads under the legs or some two sided tape to put on the feet to help secure it to the floor it may be slipping on the new floor surface

Check the pump for debris .

Suggest use detergent designed specifically for your model.

4 screws takes the front off the washer to find the leak, dryer probably needs drum rollers. If you didnt know maytag went bankrupt for a reason

all the bearings in your washer are sealed for life type and your right it is a bearing thats wearing out

two problems here,
your shaft seal is running on its last leg
the sound is unmistakeable and always described the same...
the water issue, you probably have a trickle leak through the cold water valve
the mixing valve is quite an easy repair, but I would have to say with all honesty, it probably time for a new machine
the hub seal is a tub replacment call
2 hrs of labor if hes good
and the tub runs around 500.00 dollars
sory for the bad news

Rear shocks tend to wear faster than the front.
Try switching the front shocks to the rear. If this helps, plan on
buying 2 new ones. You will have time to search for the cheapest price... typically 25 USD @ /www.appliancepartspros.com/