Rav Yisroel the son of Rav Duvid Moshe of Tshortkov once related how Rav Levi Yitzchok of Berditchev once came to visit Tshortkov several years after Rav Hirshele Tshortkover had already passed away.
During the Kedushas Levi’s visit he davened in Rav Hirshele’s Kloizel, however, being a chassid, as was his custom he davened nusach Sefard, which was contrary to the established custom of the shul.
No sooner had Rav Levi Yitzchok, well known for his passionate fiery tefillos, begun to daven Sefard he was seized by a deep sleep in which he had a visionary visit by none other than the Rav of the Kloizel, Rav Hirshele Tshortkover himself! Rav Hirshele appeared to the Berditchever Rav and admonished him for switching from the nusach Ashkenaz rite to Sefard and challenged him thus:
“How dare you! What gives you the might and right to change from nusach Ashkenaz in this place? I worked very hard, and I struggled and exerted much effort until I succeeded in forging a pathway ascending heavenward through Nusach Ashkenaz!” so saying he concluded his visionary rebuke and the Berditchever awoke and switched promptly back to nusach Ashkenaz!
“Now see that?” concluded Rav Yisroel of Tshortkov, “We all know how passionate and moving the heilige Berditchever’s tefillos were, yet somehow Rav Hirshele was so great that he could even induce a sleeplike trance on the Kedushas Levi to get him to change back to the correct nusach haTefillah!”
On a different occasion years after Rav Hirshele’s passing, when someone tried to switch from saying Bameh Madlikin on Shabbos Friday night to Kegavna like the custom of nusach Sefard, that night a fire broke out and consumed the amud where the chazzan prayed as well as the floor he had stood upon up the aron hakodesh where it stopped and ceased. Needless to say that they reverted back to Bameh Madlikin, even many many years later when the worshippers did daven Sefard they still kept to saying Bameh Madlikin, so as to prevent another hadlaka! (Shemen haTov 101-105 Sefer Thsortkov pg 171)