Why does it say "Gam"?
Radak: In addition to the Kavod mentioned. That was lost when they broke it. Afterwards, they will take the gold to Ashur.
Radak citing Rav Sadya Gaon: This includes the calf in Dan. It was exiled first.
Malbim: At the same time that Melech Ashur took Hoshe'a ben Elah and incarcerated him, he took also the calf.
When will it be taken to Ashur?
Rashi (from Seder Olam 22): It was in the 12th year of Achaz - "va'Ya'ar Elokei Yisrael Es Ru'ach Pul Melech Ashur... va'Yaglem la'Reuveni..." (Divrei ha'Yamim I, 5:26), and he took the calves in Beis Kel, to fulfill "Gam Oso l'Ashur Yuval." Radak - Yuval is like "Yuval Shai" (Yeshayah 18:7).
Who is "Melech Yarev"?
Rashi: It is Sancheriv.
Radak: It is Melech Ashur. His name is Yarev.
Radak citing Targum Yonasan: The king that will exact payment from (quarrel with) them.
What is the meaning of "Bashnah Efrayim Yikach"?
Rashi: Yaravam, who is from Shevet Efrayim, will take shame, for he erected this calf for a god. Radak - Bashnah is like Bushah; the Nun is extra.
Malbim: He took the calf, which is the shame of Efrayim.
What counsel is shame for Yisrael?
Rashi: The counsel to make the calves - "va'Yiva'etz ha'Melech va'Ya'as Shnei Eglei Zahav" (Melachim I, 12:28).
Malbim: The counsel to rebel against Hoshe'a and hand him over to Ashur. They thought that this will return Avodas ha'Egel. This caused the Egel to cease totally!