What is "Meginas Lev"?
Rashi #1: It is a broken heart, like "Amagenecha Yisrael" (Hoshe'a 11:8), "Asher Migen Tzarecha b'Yadecha" (Bereishis 14:20). Ibn Ezra #1 - if so, there is no need for the Dagesh in the Nun. Its grammatical form is like Achilah.
Rashi #2: It is a sealed heart. Affliction and sadness is like a shield opposite the heart.
Rashi: Some say that is an expression of Tugah and Yagon 1 (sadness).
Ibn Ezra #2, Rid: It is from the root "Ganon v'Hitzil" (Yeshayah 31:5). This is correct. (The Dagesh in the Nun compensates for the missing Nun.) It is a covering over the heart; they will not see the curse 2 that You will bring upon them.
Rashi: This is wrong. If so, there is no reason for a Nun in Meginas. It is not from the root of Yagon! Rather, [the Nun in Yagon] is like the Nun in Hamon, from the root "Hamu Goyim" (Yeshayah 29:7), and the Nun of Tziyon from the root "Tziyah" (ibid. 41:18). Rid - based on context, it means Yagon (sadness. He did not say that it is from that root. - PF)
What is "Ta'alasecha"?
Rashi: It is an expression of folly, like "No'alu Sarei Tzo'an" (Yeshayah 19:13).
Ibn Ezra: It is Your Alah (curse). Rid - it is like "Es Kol ha'Alos" (Devarim 30:7). The Tov is extra.
Ri Kara: It is like Tal'asecha. All the suffering that You brought on me, bring on them. Every Aleph Beis (the first four Perakim) ends with a request to do to the nations like You did to me.