VW Golf Jetta Mk5 1.9TDI Stalling Long cranking No/Hard start, Crank Sensor P0321 P0322 Waveform A4

This is how I found and fixed a crank sensor issue on my VW Golf Mk5 1.9TDI (Rabbit/Jetta).
This video includes a good crank sensor (Engine speed sensor G28) waveform from a VW, Audi, Skoda, SEAT, VAG, 1.9tdi diesel engine code BXE, BKC, BLS (I believe) and possibly others.
The fault was caused by a broken earth wire between the crank sensor and ECU that had been causing intermittent stalling (especially when slowing for junctions and traffic lights), hesitating, hard/poor starting, stalling when pulling away after start. It was worse when the engine was warm. It was also sometimes triggering a fault code P0321 or P0322 but not always. VCDS seemed to show good engine speed sensor G28 signal but I think it was using the G40 cam sensor signal to provide this when it was getting a bad signal from the crank sensor.
I found the broken/worn wire by connecting my cheap £25 Amazon oscilloscope by back-probing the signal (purple) wire at pin58 of the ECU. See wiring idents at the end of this description. With the engine running I wiggled the 3 crank sensor wires in the loom BEING VERY CAREFUL OF THE FAN!!!! The signal kept dropping out as I wiggled the wires where the loom passes over the starter motor/gearbox area due to the blue/brown sensor wire being worn and almost broken. I also could probably have found this by resistance checking the wires from the sensor to the ECU with a multimeter but the sensor is quite hard to access. It sits behind the oil cooler housing which has to be removed to access the sensor.
This took me a while (weeks!) to figure out after replacing the crank sensor twice, the fuel lift pump and the fuel tandem pump. I wrongly went down the fuel route because I read somewhere that extended cranking times can cause a crank sensor code when the crank sensor signal is fine and the fault lies somewhere else. The first replacement crank sensor I fitted was an aftermarket one and made no difference. The second replacement was an OEM sensor and did improve the fault but due to the broken/worn wire it was never going to fix it completely. So this supports what I have read that if the wiring is good then always use an OEM crank sensor, from VW ideally, as the aftermarket ones may not be as sensitive or give as good a signal or be more affected by heat.
Hope all my mistakes can help someone else!
Crank sensor to ECU wiring for Mk5 Golf 1.9TDI BXE engine:
Crank sensor Pin1 - Black/red wire - ECU Pin42 - 5V
Crank sensor Pin2 - Purple wire - ECU Pin58 - Signal 0V to 5V square wave
Crank sensor Pin3 - Brown/blue wire - ECU Pin57 - Earth
Oscilloscope (comes without power supply)
www.amazon.co.uk/dp/B07P7KQLK...
9V Power Supply (UK plug with 2.1mm DC jack plug)
www.amazon.co.uk/dp/B07Q3KKWG...
9V Battery Adapter (with 2.1mm DC jack plug)
www.amazon.co.uk/dp/B01MY9RXI...

[@GrubbyRabbitRepairs]

I forgot to say - WATCH OUT FOR THE FAN COMING ON when wiggling any wires or doing anything in the engine bay!!!