Geeetech A30 auto-level troubles

[ohilveti9]

Hoping someone can give some advice here. I had an A8 which had plenty of issues, so I got an A30 a few months ago as something that would just "print decent out of the box with minimal fussing". Plenty of good reviews on this thing and it was good for the first month or so. I'll spare the boring details but basically the last saving grace is to get the the auto leveling working. My bed is scratched to shit and it's higher in the center and I'm now having trouble with PLA sticking when getting further from the center - so no big, offset or multi-part prints...

It came on firmware v1.35.56, and I have an NPN sensor installed, but I keep having issues when trying to do the auto-level setup, the sensor itself seems to work fine, but it just crashes the nozzle into the bed every time - I think this may just be a bug with the firmware version. However, I updated the firmware to the latest stable, but the Smartto motor tool will no longer persist step changes - which I need because the default extruder steps are way off and I was getting a lot of under-extrusion, so I went back to the version it came with. Anyone have any advice on the auto-leveling or step config?