My hotpoint wd420 has started violently starting bouncing ?

Mine did exactly the same - I have the WD860 so things may be a little different but its easily fixed. There are 2 screws holding the top cover on the washer dryer, they are at the back on either side - unscrew and remove the cover (obviously make sure power is off). With the top cover off, you should be able to see a concrete counter balance on top of the drum with 3 bolts in - I found that these bolts had come loose on my machine and led to the concrete block (and washers underneath) moving around and making a loud noise and the machine moving excessively. I just nipped these bolts up and the machine is spot on again.

Hope this helps, I checked the other things whilst open - like the springs etc but they were all ok but for you a spring may have gone.

Good luck

Jimbo
August 2010