This is on version 1.04
I had a basic line running using all the starting slots.
After i had researched “body specialization” i split off the conveyer after building the chassis and added the three new slots, run the conveyer round and connected it to the paint-slot.
The old complete “fit body” slot was still there when i did this. Then i removed the “fit body” slot and fixed the visual errors on the conveyers.
The problem is once a car run through the “fit door”-slot it just stays there with the error “Next slot not found”-message, but the paint slot is properly connected. Deleting and redoing the conveyer between these two slots didn’t work. I tried deleting and replacing the paint-slot but then the game crashed (maybe thats the crash on looped-belt problem that is already fixed for the next version, so this might be related).
My guess is the problem is that the “fit body” slot was still present when i connected the initial conveyers all up, messing up the internal slot-order or something.