The purpose of hearing the Shofar is to arouse feelings of Teshuvah.
There is a dispute whether to commence blowing the Shofar on the first or second day of Rosh Chodesh. Minhag Chabad is to make a point of practicing the Shofar on the first day of Rosh Chodesh, (thus hearing the Shofar in an informal way,) but to begin blowing it formally only on the second day of Rosh Chodesh.
Our custom is to blow ten sounds. [Tekiah-Shevarim-Teruah-Tekiah; Tekiah-Shevarim-Tekiah; Tekiah-Teruah-Tekiah.]
If one was unable to hear the Shofar with a Minyan, he should still endeavour to hear the Shofar.
During Elul, one does not need to repeat the sounds if the Shofar was Possul (e.g. it had a crack or hole). Similarly, one does not need to repeat any sounds blown incorrectly (e.g. the Tekiah was too short). If the Ba’al-Tokeah chooses to fix his mistake, he certainly does not need to redo the entire section, as he would were it Rosh Hashana.
