Just gone through same with my 2gm20c and you can see thread in this forum. The end result was that Yanmar
quote was for NZD 1200, the after market starter we tried from a Chinese supply fitted but failed after only a few starter engagements which cost NZD300 for each motor
we tried. The last motor fitted is an American supply from MASCO which is now fitted and looks considerably more substantial than the Chinese supply but cost more as you might expect. The total for the MASCO starter being exported to NZ was NZD 450 but the retail cost in the US was USD229.
We are now up and running