What goes behind this cover on a Harlie Rake?

[FTG-05]

I rented a Harlie rake from my local equipment rental places. Made a pretty good circle around and found the gearbox/chain cover on the ground. See the "York" cover in the first few minutes of this video*:

I'm going to reattach it this morning. Is it supposed to be full of grease? Just grease the chain? Just put it back and pretend nothing happened?

* The difference between this York rake and the one I have is that the cover is held on my one 1/2" bolt, which apparently came loose, then undone and the cover fell off.


Thanks!

 

[North Idaho Wolfman]

Lube chain then put the cover on.
If it sucked in a bunch of dirt spray the chain down with brake parts cleaner before lubing it.