What could have changed to screw up first layer?

I have a prusa i2, marlin firmware, slic3r, and using repetier host. Printing ABS.

I pretty much had the first layer dialed in perfectly set first layer to 'default' which is 200% extrusion at 40mm/s and calibrated the bed using a 0.2mm thick piece of paper I found. I had to take the bed off to repair a broken wire for the thermistor. I put it back and calibrated the bed with the same piece of paper to set the clearance. when starting a new print the first layer was really bad visible spaces between the traces and barely sticking. I've since used a 0.1mm piece of paper to set clearance and upped the first layer extrusion to 300% and still doesn't look as good as what it used to. I got a print going now... we'll see if there is enough meat there to make it stay stuck to the bed. I've rechecked settings to see if anything is off, triple checked the bed spacing, made sure there was no gunk on the bottom of the nozzle to throw off the calibration. This is driving me a bit nuts. Anyone have any ideas??

If the other layers print fine it's the bed leveling thats off, or the extruder needs extra lead time to get up to speed, increase the number of loops.

Did you try leveling the bed while it's heated to abs temperature? This can make a noticeable difference.

When this happen to me a good, thorough cleaning of the bed with alcohol usually do the trick.

I can't think why you would set the nozzle gap with a 0.2mm thick piece of paper of paper - much too wide. Even when using the 0.1mm paper piece, you should feel the paper "drag" a little under the nozzle (it's probably around 0.07mm). And as mentioned above, heat your bed and in particular your nozzle (suck the filament back 10mm or so beforehand) and set it up then. A nozzle gap can be significantly different between hot and cold.

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Waitaki 3D Printer