I'm having trouble understanding how to use this. I have a condenser, I've put a bunch of other condensers into it with an inserter and set the module slot to be a tier 1 quality module. Nothing is happening and the instructions say there should be multiple slots so I'm sure I've done something wrong.

1) place condenser
2) add some quality modules into the module slots
3) fill the inventory of the quality condenser with items
4) wait a few seconds
5) the machine should start animating
6) when its done you should have higher quality items

Okay, I did that. Half the time it doesn't do anything (I know it takes a moment to start) and then it just ate two stacks of an item (electric furnace, stack size 50) to return 1 at uncommon. I wasn't aware the ratio was quite so bad but it appears when it wasn't doing anything I just had the wrong number of items in it (there is only a single module slot, not multiple as implied in your comment), I'll wait until I get to Fulgora and use recyclers ;)

Thank you for taking the time to make the mod though, it's a really nice idea.

why does everyone keep confusing the module slots for upgrade slots, i meant if you have a higher quality condenser it gets more inventory space, aka slots to upgrade, all at once :D

and the rate gets better when you put a better quality module in there ofc, if you have a 1% quality module and put in 100 items then you get one.

If I mouse over the module slot the game literally says "module slot"; I suspect that'll be the reason and if you can rename that it'll probably help prevent that happening in future. I understand the higher quality condenser has more inventory space but that very much wasn't the issue.

So what is a module slot and what's an upgrade slot, I'm really not sure which is what. Screenshots would probably help on this one too; especially if I'm not the first to have this confusion.

I cant get it to work either.
90% of the time its "disabled by behavior". it only randomly seems to turn on for a single cycle with no apparent cause.
The inventory is like a chest, it just takes things in and out constantly.
even if it runs nothing ever happens to anything in the inventory even if you just put things in there and have no inserters to remove or add more.

disabled by control behavior is not a bug

disregard.
I uninstalled immediately after reading your other recent comment "it only works after doing nothing for a few seconds".

allright glad it's working for you now