What is the job of the Makri? It is customary to have a person [i.e. Makri] utter the name of each and every blow to the Baal Tokeia [i.e. the person blowing the Shofar] prior to him sounding that blow. This is a fine custom. [Nevertheless, according to the Chabad custom, the makri does not utter a word, and instead he merely points one by one to the names of the sounds as listed in the Siddur. This custom applies to all Chabad Minyanim and not just to the Minyan of the Rebbe’s Shul in which the Rebbe is the Baal Tokeia. The Baal Tokeia sounds the blow for as long as the finger of the Makri remains on the sound.[
Who should be the Makri? It is customary that the Chazan which Davened Shacharis is also to be the Makri for the person blowing the Shofar. [If however there is a Rav present in the Shul then he is to be the Makri. Practically it is not the Chabad custom to be particular that the Chazan of Shacharis be the Makri. It is of much importance that the Makri be a person of stature, a Tzaddik that is expert in the Kabalistic meanings of the sounds. This is in addition to the necessity for him to be an expert in the laws of the sounds that are explained in chapter 590.]
It is customary to have a person direct the Baal Tokeia as to which sound to blow. The Chabad custom is that the makri does not utter a word, and instead he merely points one by one to the names of the sounds as listed in the Siddur.
Spiritual Preparation of the Makri:
The Makri is to spiritually prepare for the blowing just like the Baal Tokeia. He is thus to separate from impurity for three days prior to R”H.
Makri for Musaf:
It is not the Chabad custom to have a Makri point at the sounds by the blows in Musaf [both silent and repetition] or after Musaf.
May an Avel within his year of mourning be the Makri?
 Admur ibid based on Rama 585/4
Is the Makri to recite even the first blow? Saying the names of the blows is not considered an interval between the blessing and the Mitzvah. [Teshuvos Rosh 4/18; Kneses Hagedola; Peri Chadash 585] Thus he may recite even the first Tekiah to the Baal Tokeia. [Shlah p. 214a [based on reason mentioned below]; M”A 585/11; Elya Raba 585/15; M”E 585/5; Kaf Hachaim 585/46] However some Poskim rule that it is best for the Makri not to recite the first Tekiah in order for it not to be considered an interval between the blessing and the Mitzvah. [M”B in Shaareiy Tziyon 585/31; Shlah ibid says that this was the widespread custom not to sound the first Tekiah.]
How are the words sounded? Some write that the Makri is to sound the beginning Tekiah in a starting tone while the end Tekiah in an ending tone. [Luach Eretz Yisrael] The Makri must be careful not to begin saying the next sound until the current sound has ended. Likewise the Baal Tokeia is not to begin the next sound until the Makri is finished reciting the word.
Shevarim-Teruah: By the Shevarim-Teruah some are accustomed for the Makri to say it in a single breath by the Meyushav blows and in two breaths by the blows in Musaf in order to hint to the Baal Tokeia the breaths to take in that set. [Alef Hamagen 590/22 in name of Mishmeres Shalom]
 The reason: This is done in order to avert confusion of the blower and having him accidently blow the wrong sound. [Admur ibid; Rama ibid] Asides for the above mentioned reason there are great Kabalistic reasons behind having a Makri [Shlah ibid; Aruch Hashulchan 585/8] as each Tekiah and Teruah arouse a certain Divine level. It is the job of the Makri to intend the mystical effect of each blow prior to it being sounded. The Baal Tokeia than sounds the actual blow on the basis of that Kavana. The effect of the sounds is dependent on the Kavanos of the Makri. For this reason it is of much importance that the Makri be a person of stature, a Tzaddik that is expert in the Kabalistic meanings of the sounds. [Shlah ibid] Alternatively the reason is because it corresponds to the sounds of Matan Torah of which it states that Moshe spoke and Elokim answered, hence having a Makri and Baal Tokeia. [Chochmas Shlomo 585]
 Sefer Haminhagim p. 119 [English]; Igros Kodesh 5/109; Hayom Yom vol. 2; Sefer Hasichos 1944 p. 3; Reshimos 4/8; Otzer Minhagei Chabad p. 119
The vintage Chabad custom: The old Chabad custom was to have a Makri which intones the blows to the Baal Tokeia just as is done in other communities and is ruled in Admur ibid. This was the custom in all Chabad Shuls. The Rebbe states that when he was in Rostov by the Rebbe Rayatz he for the first time saw that the Tekios were performed without a Makri that stated the words. [Hamelech Bemisibo 1/235; Otzer ibid; See statement of Rav Avraham Chaim Nah brought in Igros Kodesh ibid]
The lack of a Makri: There were years that the Rebbe Rayatz served as his own Makri placing his finger on the sounds as he proceeded with the blows. [Sefer Hasichos 1945 p. 3; Otzer ibid that for many years, from 1974-1978, there was no Makri when the Rebbe blew Shofar.]
 Igros Kodesh ibid in answer to a question of Rav Avraham Chaim Naah that seemingly the custom only applies when the Rebbe is the Baal Tokeia and not to other Minyanim.
 Otzer ibid that so is the custom; However see there letter 272 that when the Rebbe was Makri he removed his finger and placed it on the next blow during the current sound.
 Admur ibid based on M”A 585/11; Darkei Moshe 585
 Peri Megadim 585 M.Z. 7; M”B 585/31; Kaf Hachaim 585/47
 Otzer ibid
 Shlah ibid; Beir Heiytiv 585/7; M”E 585/2
 M”E ibid
 M”E 585/2
 Otzer Minhagei Chabad 328
Other customs: The widespread custom is to have a Makri by the blows sounded in the repetition of Musaf and after Musaf. [See M”E 592/9 and 11; Mishmeres Shalom 41/7; Likkutei Mahrich 70b] One may certainly however not have a Makri recite the words during the silent prayer of Musaf. [Minchas Elazar 4/37; Sdei Chemed R”H 2/16] However some are accustomed to be lenient to have a Makri even during the silent Shemoneh Esrei. [See Otzer Minhagei Chabad 328; Piskeiy Teshuvos 585 footnote 68]
May the Chazan of Musaf be the Makri? Some Poskim rule that if the Chazan of Musaf may not be the Makri for the Tekios due to it being an interval. [Shaareiy Tziyon 585/30 in name of Peri Megadim] However some Poskim argue that even the Chazan may be the Makri and it is not considered an interval. [Levushei Mordechai 4/37; See Elya Raba 585/15]
 Mishneh Halachos 10/70; Piskeiy Teshuvos 581/13
 As the Makri does not actually say the words according to the Chabad custom.