What are the difficulties historians face in using manuscripts?

A manuscript is an especially handwritten or typed document. and it is a writer's first version of a book before it is published.

Historians face several difficulties in using manuscripts. 

Due to the unavailability of the printing press in those days, scribes copied manuscripts by hand.

Manuscript copying is not an easy job. because each and everything need to be handwritten.

Historians face several difficulties in using manuscripts There was no printing press in those days so scribes copied manuscripts by hand. And copying manuscripts is not an easy job. because each and everything need to be handwritten.