I created an assembly in Solidworks, which i wanted to import into Sketchup. However Sketchup doesn’t import .sldassm files so ive converted them to .3ds using 3DMax. From there i would import the .3ds version of my product into Sketchup. This is where the error seems to begin or becomes visible.The file has missing components. Even with changing the export/import configurations i always receive the same results.
You could try some other format instead of the rather antiquated 3DS. If you have access to Rhino, for example, it can import a STP and save it directly to a SketchUp file. Or try saving as a DWG from Solidworks.
You may also want to try MoI3D importing a STEP file from SolidWorks and then exporting from MoI as SKP. MoI has nice tessellation controls for the SKP export.