Just got my neptune 3 pro and the back right corner was so low it failed when auto leveling after the first calibration. It was off so much I could see the problem.

Loosened the bed plate screw and could tell it was under too much pressure as the bed raised close to 4mm. I reran the auto leveling calibration with the screw loose and it finished without an error and was much more level across the entire bed.

I put a couple of #8 washers under the heat plate and on top of the existing tube support to maintain the height needed and the problem is that the original screw is now too short to engage the bed support structure.

While it is now printing fine, I would like to be able to have the bed plate secured fully on that corner rather than only the remaining 3 places.

Can anybody let me know what screw size it takes so I can buy a longer screw for that?

Thank you for any help.