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Glad to hear another success. I guess your issue is something related to power supply. Try it with a 4-5A power supply and adjust the stepper driver(A4988)'s output current to get a better precision. Regarding the SMD PCB prototypes, 28BYJ and DVD step motor might not provide the precision you need. Better get 200 steps/rev steppers.
Use a multimeter you can determine where's the Phase A and Phase B. https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z0000019LWZSA2&l=en-US
The easiest way is to google the model number on it and see how many steps per revolution
You will have to disassemble and see what stepper motor in it.
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