I bought mine 24.10.2019 and got it repaired on warranty 11.2022 by the shop that sold it to me. The consumer regulations are 5 years here, no matter what. It started thumping constantly every 2 sec or so.
The repair shop has cut and removed the wires to the 120v-220v switch.
There is no longer any thumping, so it seemed to do the trick. Its now locked at 220v setting. I am not aware of any other mods they did, have a few pics but did not spot anything else.
However, i am now running the sub off a so-called master/slave power strip, it will not get power, unless the TV is on. From what i hear, these subs should never be on standby power, it will reduce their lifespan severely. Because their caps will boil.