Add 45 RPM to an LP12

I have an old 1970’s Linn LP12 - US, 33 RPM only, square orange button, 60 Hz motor. I just want to add 45 RPM capability at this time. I am hoping an experienced Linn expert can suggest a simple, easy, cost-effective way to accomplish this among the many possible solutions that are available. The many choices, upgrades and sources have me confused. Thanks in advance for any help.