Hi @aleki16656
Search online for either [https://www.google.com/search?client=firefox-b-d&q=LB302260|LB302260] or [https://www.google.com/search?client=firefox-b-d&q=V6557600|V6557600] to find the 12V DC-In power jack suppliers that suit you best.
These are the part numbers for the jack as shown for Ref.# JK151 on p.46 of 52 (pdf) of the [document|42304|service manual] for the keyboard - also see the wiring diagram on p.8 of 52