Starter meshing issue

[GTOBEN]

I have a mini with a 1430 engine which I believe started life an A+, however I am having problems getting a starter motor to mesh with the ring gear properly!
I think the engine started life as an A+ series, however I have a pre verto clutch and flywheel assembly. I have tried both inertia type and pre-engaged starters but both do not mesh properly.
Is the casing around the flywheel different on the later type engines, and could this be the problem?

Any help appreciated as I am not sure whicj way to go with this now?

Thanks
Ben

[Cooperman]

Assuming the pre-Verto flywheel also has a pre-Verto starter ring (i.e., it's as original) then you must use an inertia starter motor.
The casings are all the same dimensionally and the only real difference is the diameter of the transfer gear bearing between early & late cars.
Check the condition of the ring-gear teeth and the starter pinion teeth.