I’ve got a Hotpoint Aquarius WMA 33 which has worked for many years. And it’s gone wrong.
As far as I can tell, it’s just not spinning. It’s plugged in and switched on. Water feeds through just fine, but the drum doesn’t spin at all. The only noise is that of the water.
Where do I start to diagnose the problem?
Have fun! Have you opened it up yet to see if there are schematics stored in the back? Some have diagnostic proceedures or flow charts in them. If you’re not good with electrical schematics and a meter, I suggest a repairman. It could be the door switch, the electronic control panel, or the motor to name a few. If not diagnosed properley, you could replace the control curcuit, only to blow it again by not catching the short in the motor. (Ask me how I know…).
later, Tom.
I was incorrect when I said that there was no sound other than the water. There is an electric hum coming from the machine and it does sound like something is going round. I did note that I could not rotate the drum by hand when the machine is loaded with wet clothes. I put it on a spin program unloaded and it still does not spin.
Too many possibilities to diagnose it here. I’d actually suspect some failure in the gearbox below the tub but a hands-on assessment is required.
doesn’t look like this was ever offered in the US, so my usual lookups for diagrams aren’t being too fruitful. looking at some UK parts sites, it looks like this model is belt driven? if it is, and the belt broke, it’s likely that you’ll hear the drive motor running but no agitation or spinning.
edit: and even if that is true, there’s still the chance that something in the drum is binding which would likely cause any belt to break.
The most common of failures in older washers is the timer that causes the various functions to happen in sequence.
The first function is to fill the machine. That is happening for you, but nothing else. That humming noise may be diagnostic. If it sounds like it could be the motor trying to start, that would mean the motor could be frozen and need replacing. That’s quite expensive.
Another common and cheap failure that would keep the drum from spinning is the simple door switch. That switch is depressed by a tab when you close the door. It may be defective or out of adjustment. Find the switch and try pressing into the place where the door tab goes in an attempt to activate the switch. If that works, the door tab is out of adjustment. If it does not work, the switch could still be bad and you would need to jump the connection across the switch to check this theory.
As I say, the timer is the common problem.
You can get information including diagnostic help and parts at:
http://www.repairclinic.com/
Could be as simple as a broken drive belt, the hum you hear would be the motor spinning freely, you will not know for sure until someone take a look inside the machine.
I had the same problem with mine this summer. It was caused by a worn out drive coupler. Once I found out what it was, it was easy to fix. Our local hardware store had the replacement part for less than half of the best price I could find online.
Here’s where I found the info on the part and how to replace it.
(Link goes to fixitnow.com).
If your washer is a belt-drive, the fix will be different, of course.
ah yes, the Whirlpool drive coupler 
if yours hasn’t broken, you haven’t had the washer for very long…
I got home an hour or so ago, pulled out the machine, and took off a small panel at the back. I had a feel around inside and the drive belt has come loose. I don’t know if there’s further damage. But to fix it, I’m going to have to take the whole back off and I’m not sure how to do that. Can Dopers advise?
This book is out of print, but as you can see from the link, used copies are still for sale out there. I can’t tell you how many times I’ve used that book to successfully diagnose (and usually repair) home appliances. It’s especially good with washers and dryers.
It may be that the Web has rendered it obsolete, but I still think it’s handy having all that info between the covers of a single book.