When I was downloading the sketches and libraries I noticed there was both a box_1-src & a box_2_src sketch. I used the first one per the instructions but wondered why the two? I've put them up in the editor to compare them and can't see any difference!
I found the default P&T default of "1" at lines 113 and 114 too slow and after some experimentation settled on 5 as a compromise.
The Next and Last buttons work well but I have yet to see any difference using the "Fine" button.
I used a 3D Printed panel so it looks pretty good but wish there was a commercial USB Encoder box that was a lot more robust. I also use Alien Stagecraft’s “oscRFR” (For Android systems) but don't find the touching the LCD as intuitive as the boxes wheels.
The box has been in use for a couple months now and is a boon to ELE2 users that need the Encoders.
The authoritative source for the lighthack sketches is on the lighthack GitHub: https://github.com/ETCLabs/lighthack
This repository contains only one sketch, box_1_src.ino. I am not sure where you got something called "box_2_src".
If the Fine button is not working, it's likely that you have a hardware problem. I recommend following the troubleshooting steps in the assembly instructions, especially the line "Device mostly works but a button or an encoder is not working".
Hope this helps!
Your right on the box_1_src. Hmmm. I hate having to do it but looks like the lid is coming off. Darn