I never have luck with 555 timers so I got into looking for a alternative solution. A friend told me to use a gate clock setup but that wouldn’t work so well from my research but I came across a robotic website on a simple schematic for a 74logic 7414 hex schmitt-trigger inverter. Uses less parts then a 555 PWM controller and has a better duty cycle range. Just need to toss on a fet or resistor on the base, ground out the emitter and send the pulse to the collector. I could even make this work on a extra pin on a ULN2003 to save space.
PWM output to motor.
Quick example if I wish to use the ULN2003 instead since I would have three unused I/O on my CNC project controller board that I attend to use this circuit on.