Many clips in different projects were missing but the pictures were there!
I have managed to convert, if that is the right word, all the project and events files and the iMovie 10 Library now contains 950 GB and the iMovie theater 4,16GB because most of the uploaded files are not in the theater file. During the upload process there were several error messages saying that not all the files were compatible (with ? El Capitain or iMovie 10?) although I could find them in the iMovie 8 files and in iMovie 8 the clips were there but the images not!
I tried convertingit one file at a time but as I said I did not know all the event files for a particular project and those which had a single file in each section (project/event) ended up with missing clips which I could not get them to recognise although I reloaded the clip.
I just think that the conversion does not work properly either because of 10 or El C.?
I have reinstalled both the Os and iMovie 10 so unless there is a bug in the computer or more likely the applications I just cant get any further. It is a pity Apple does not read all these fora - they might write a fix if they knew.
There was a further problem with iMovie 10, the first time I opened it it hung, I forced quit and then opened it again and it worked. This alternating working and hanging seemed to persist during the entire process which I have been at all day!
In desperation,
William