Slic3r gcode going nuts

Earlier today I could print with gcode output by slic3r. I tried many things to adjust the settings to get better quality on the top layer. At some point slic3r started messing up the gcode.

Now when I try to print something, the bed goes up, then down again, then starts extruding in the empty air far above the print bed.

It's not the printer. I tried a file that I generated yesterday and it printed just fine.

I tried resetting everything back to the defaults in silc3r. Even that didn't work. Even with Print Settings, Filament Settings, and Printer Settings reverted back to their defaults, I still get the same behavior.

Does anyone know what's going on? I messed up something, but I have no idea what.

Check under "Print Settings">Support material">"Raft layers" and ensure that is set to 0. If that's not it, post the first 50 or so lines of a file that works and a file that does not and I'll see if I can spot the difference - or try yourself by opening the files in a text editor and comparing settings - all the main settings are in the file as comments. A change to the custom start code is often the culprit when things mess up.

Dave

Found it!

Works:
G1 Z0.3 F6000.000; move to first layer height


Doesn't work:
G1 Z100% F6000.000; move to first layer height

The problem is that I set Print Settings->Layers and Perimeters->First Layer Height to 100%. I'd had it at a set number before. The reason why changing back to the defaults didn't work is because the *default* is 100%, which is why I changed it in the first place. D'oh!

Thanks for the tip. I should probably always keep one that works around, in case I mess up again.