Usage of 'the various trash-planet worlds' implies that these are specific trash-planets, which doesn't seem to be borne out by the rest of the rules. Probably best to remove 'the' from that sentence. Dice and models used should probably be specified somewhere in the rules. The durability chart could be simplified by including durability ranges per effect to the rows for each component. The scrap blunderbuss's ammo cook-off probably means that the blunderbuss can be thrown as a grenade, rather than a 'grande'
Okay so minor edits aside, I quite like this system. It's not got a ton of depth, but it would be pretty trivial to expand, and makes for a fun quick little mech brawl. The weapons having a surge of power at the end eludes to the Jam's theme, but the game doesn't really otherwise go much in for the theme. It's a burst of power near the end, it's not changing the notion that as you take damage you get closer to the failure state. It's also not a wildly original game, but the design is the pleasant and cunning sort of simple, which is a strong endorsement.