Note:
You are going to need all 3 printable files.

Assembly guide:

Begin by assembling the chain and leaving the last connector empty. You will have to alternate between using empty and bucket sections. Make sure that the buckets are on the outside of the chain. In order to interlock modules, use the module connectors (smallest shafts on the print).

For this section you can use the images provided below as reference. Take the wall with the rounded opening at the bottom and the long connectors at the top and place it connectors up on your desk. Insert the 2 medium shafts in the top and bottom inner holes, and then place the cylindrical gear (the 2 gears merged into one) on the bottom shaft. Continue by wrapping the chain around the gear (while also matching the chain teeth with the gears) and then, before closing the chain with the final connector, place the gear on the shaft, wrap the chain around it, and only then close the chain. Finish up the chain mechanism by locking it into place with the last remaining gear.

Now you can take the wall that has the ramp attached to it and and connect it to the rest of the assembly. Make sure that the ramp is inside of the 2 walls (inside the chain as well), and also be wary of the bottom connectors.

Place the whole assembly on a flat surface (with the just placed wall facing up), and make sure that the 2 shafts are sticking out. Now you can place the small spacer on the top shaft and lock it in place with the small gear. Then, take the last remaining wall and connect it to the rest of the assembly.

Now for the hardest part, take the remaining spacer and large gear and stack them in between the 2 walls, with the spacer on the same side as the small indent (same order as the previous gear and spacer) and lock them in place by running the large shaft through both of them and pushing it all the way through so that it sits nicely in the indent. 

All you have to do now is take the hand crank lever and stick it onto the large shaft, and you should now be able to engage the chain with the hand crank. 

If you want to test the system, insert a bottom through the bottom gate and watch it get lifted up and then dropped onto the ramp.

Enjoy :)