Again, difficult for me - too many errors building the thing at my age with eyesight and senility! I think good quality kit makes a big diff here though with non exact values for some caps and resistors throwing out timing multiples for even steps etc? - too much noise for clarity in the fine divisions to get a clear stair step. Best I got was uneven and spiky spread at the trigger start:
Arduino, Amps, Kits etc.