Here is the version of the story as quoted by Rabbi Frand at torah.org.
A "Chassidishe Story"
Finally I would like to share a true Chassidic story involving the Klausenberger Rebbe, zt"l. This is an incident that happened shortly after World War II. The Klausenberger Rebbe made it out of the concentration camps. He gathered together a small community of followers who also survived the Holocaust and from this small group, he eventually rebuilt the whole community.
We are all familiar with the near universal custom that when the Torah reader reads the Tochacha in both Parshas Bechukosai and Ki Savo, he reads it in a subdued tone. We rush through it, as it were, and do not interrupt to give extra aliyos within those sections. We read it in hushed tones, as if to say: "If we read it quietly maybe it won't happen."
It was Parshas Ki Savo in the late 1940s and the Klausenberger Rebbe was in New York with his small minyan of followers. When the Baal Koreh began the Tochacha, he began it in a low voice, as is the custom in Israel.
The Klausenberger Rebbe banged on his shtender [lectern] and said "louder!" The Baal Koreh thought that he was reading so low that no one could hear, so he raised his voice a bit. Again the Rebbe banged and said "louder!" By the third time this scenario was repeated, the Baal Koreh got the message. The Rebbe did not want him to read the Tochacha in low tones or even in regular tones, but at the top of his lungs.
The Baal Koreh came to the Rebbe after the minyan and asked for an explanation. The Rebbe responded: "This can be read quietly when you are afraid that it might happen and you don't know what is going to happen to you once it happens. We, however, have already lived through this and we are still here. This is now something that we are proud of. This happened to us and we are still in shul on Shabbos. We are still reading the Torah each week! The Tochacha is now our badge of honor. It will no longer be read silently. It will be read completely out loud! We can say 'We were there. It happened to us and we have remained Jews of integrity (ehrlicher yidden).'"
