If the machine is correctly sited and level on an even floor then the only reason it will 'shake' is if it is badly loaded. That is usually caused by under loading with heavy items or mixing one or two heavy items with much lighter garments.
If it is on a floating ( floorboards) type of floor then you will get more vibration.
All machines are now cold fill only. The simplest and cheapest way to blank off your redundant hot tap is to cut the end off one of the old pipes and slide off the screwed collar and rubber seal.
Place a 10P piece inside the collar, refit the rubber seal and then screw this back onto the hot tap.
You can also buy blanking caps but they will be much more expensive.
That which can be asserted without evidence, can be dismissed without evidence.