I have a somewhat unusual take on the 'the name got changed at Ellis Island' story. Mysimple last name "Lock" has puzzled myself and cousins for a long time, and we've individually wondered what the original surname back in Lithuania must have been. But - we've never heard an older relative talk about a name change.
My one cousin, when he first met his future mother-in-law, was asked quite forcefully by the said woman to reveal what our original surname must have been, because everyone knows that 'Lock' is not a Jewish name.
Well, low and behold, thanks to the JewishGen Lithuanian records, I've found numerous records on the Lak, Lack, and Lok family of Zagare/Gruzd/Joniskis. This has long been our family name, likely from the time in the 1830s when the Russian forced Jews to take surnames. On all the ship passenger lists I've found, the name is always spelled Lak or Lack. Here in the US, it became Lock or Locke (for the fancier cousins in Boston). On my grandfather's gravestone, it is spelled 'Lamed Aleph Koph', and I assume it has always been pronounced as the word 'lock' in English.
I told my cousin to go back to his mother-in-law and explain the good news.
Lock/Lak/Lack and Kalon/Kolon/Colon in Zagare/Gruzd/Joniskis, Lithuania
Lippman/Leapman/Leybman in Dotnuva, Lithuania
Olitsky in Alytus, Suwalki, Lithuania/Poland
Lavine/Levin in Minsk Gubernia