What are Megerah and Charitzim?
Rashi: They are matters used to afflict, i.e. a saw with many teeth close to each other and a threshing Kli with many grooves, like "Petzirah Pim 1 " (Shmuel I, 13:21), respectively.
What are Magzeros?
Radak: They are axes used to chop wood.
How did they afflict them with these Kelim?
Radak: They judged (sawed) them with the saws, like "Im Yisgadel ha'Masor Al Menifo" (Yeshayah 10:15).
What is the meaning of "v'He'evir Osam b'Malben"?
Targum Yonasan: He dragged them through the markets. Rashi - i.e. in the mud. Radak - the markets had brick floors.
Radak: He burned them where they burn (make) Levenim (bricks).
Why is it written b'Malkan, and we pronounce it b'Malben?
Radak: The writing teaches in the place of Molech; Bnei Amon passed their children to Molech - "Molech Shikutz Bnei Amon" (Melachim I, 11:7). Malkan is like Malkam; Men and Nun are interchangeable, e.g. "Mof" (Hoshe'a 9:6) is Nof, and Kimham (19:38,39) is the same as Kimhan (19:41).