I am not familiar with the white engine starters either.

I had a similar problem with an '80 240. But when I took the starter apart, I realized that, by design, the drive gear would have to be fully extended before the power would be applied to the starter motor. It turned out that the starter drive had an one way clutch that was slipping. $20 for new starter drive, and problem fixed. It finally made sense though as the slipping, free spinning starter motor was more common in cold weather and first start of the day.

I have also had the Nippondenso gear reduction Japanese starters apart and they too do not have any power applied to the starter motor until the drive gear is fully extended.