1. Export mesh as .3ds
2. Import to 3ds max 2022
3. Change to Editable Poly
3a. Turn on Xview>Overlapping Faces
then Xview>Open Edges
4. Use Mesh Cleaner Plugin as here:
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5. Add Editable Poly or Collapse to Poly to see the results.
6. Weld all vertices at 0.01
77. Turn on Xview>Overlapping Faces then Xview>Open Edges
8. In Editable Poly turn to Edge Mode
9. Xview > Select results
then delete the overlapping faces
9. Delete green remaining overlapping faces and Create them agains
10. Xview>Open Edges weld the verticies together to fix (may have to convert to editable mesh first