Nozzle started hitting bed all of a sudden (I know, I know...not this again)  

Nozzle started hitting bed all of a sudden (I know, I know...not this again)

Hi everyone, I'm sure this topic has been hit to hell by now but...I've been printing fine forever and all of a sudden I start a print last night and the nozzle pushes into the bed....

I scoured the forums/youtube etc...and so far I have (tested after each of the checks I list here):

Changed the height of the PINDA, up and down to most possible heights.

I have checked, the red light is on and it goes off when metal gets near the end of the probe.

I replaced the PINDA with a new one, just in case.

I tried calibrating Z - it starts moving the paper around.

I re-flashed firmware.

I did a factory reset, then re-flashed firmware.

I made sure the X axis was level each time by raising the assembly to the top each time.

I lowered the nozzle to about 0.3mm above the bed, then did a reset - to try to reset Z zero.

I raised the X assembly to the top until it read 210mm, then lowered it to the bottom and it touches the bed between 2 & 3mm so somehow I have lost ~2mm in my Z height, which it is trying to find by pushing into my bed...

I have checked by eye everything I can think about and cannot see where I might have lost this 2mm.

I know this has happened to me before but I cannot remember for the life of me how I resolved it - Yes, I should have noted it down but I think I went through so many processes back then, like now, that I was just relieved when it finally worked and moved on with life...

Any help would be much appreciated.

Rob