Ender 3 air printing - it's not the G code and it's not the bed tramming/leveling

I have an Ender 3 that has been (mostly) rock solid for a while. The bed carriage started to get a little wobbly, so I flipped it and tightened the eccentric nuts. No more wobble. Now, however, whenever I level the bed manually and start a print, the nozzle starts printing at about 1.4 mm off the bed (I'm guessing because I have to babstepy Z to -1.4 to get it to even think about sticking). So I stop, re-home, re-level and it happens all over again. I'm pretty sure it isn't the G-code becasue the same G-code will run fine on my other Ender 3. What would cause the printer to start so far above the home to which I just leveled it? And I can't begin to figure out why tightening the eccentric nut for the Y axis would have caused this. I was happy to have fixed the wobble it was showing but I haven't gotten a decent print even started on it since. Any help is greatly appreciated! Thanks, Dutch