The most critical factor is the Part Number (OEM Code). Tajima machines have evolved through various series like TME-DC, TFGN, and TMAR. You must provide the exact machine model and serial number to the supplier. For mechanical parts like rotary hooks (e.g., Koban or Hirose brands) and needle bars, verify if they are for 'Standard' or 'Large Hook' specifications. For electronic components like mainboards or pulse motors, ensure the software version and voltage requirements match your existing hardware to avoid circuit damage.