Bendix disengaging early

[99sh]

On cold starts my bendix disengages early after a few engine rotations and free wheels. On the 2nd start attempt the car fires right up. It happens 100% of the time and can't figure out what's going on. I replaced the spring, no change. I even replaced the entire bendix assy from an original starter, also no change. Car runs fine otherwise, I just want it to start and keep cranking on the first try.

I'm still on a 6V system. Thoughts?