Since you are using a pot configured as a variable resistor, you could use an ordinary resistor for VR1 instead, then substitute a stepped parameter as the value of VR1. That is the functionality a standard LTspice potentiometer would provide anyway.i tried to simulate the circuit but it says unknown subcircuit as seen in the attached photo
View attachment 255902
YAGBATS - Yet Another Ghosting By A TSAlso, the circuit is useless without the part number of the Mosfet to see how only one with "typical" specs works.
The important pulse voltage is not shown.