The crates in Assembly Line duplicate items and thus... they had to be removed. If you already have some crates, try extracting the items first before destroying the crate.
How do you even craft the Assembly Line machines? The recipe I found on the wiki uses crafting components from Universal Electricity.
Some of the other Universal Electricity mods look neat but they seem to lack creative endgame content. Mostly just bigger explosions. Atomic Science and Fluid Mechanics are appealing to me. I think Glitch would like to see MFFS, but there's the issue of server lag...
Especially since people have enough energy just lagg the server by keeping it on unnecessarily. Plus, do we need MFFS? Its not like people are launching missiles at each other.