What engine in malaguti f12 100cc

Hi guys, anyone know what engine iv’e got in my 03 f12 phantom i’m struggling to find a starter motor for it, sometimes it engages on the button and cranks but other time it just spins up that’s why i think staters knacked, seems better when hot

 

Iv’e found some numbers it says mitsuba japan sm-5 can anyone point me in the right direction to get one of these

 

Strip motor, clean and lube it. put a set of mole grips on shaft teeth and pull off tin cover.