Found the following hamletworks.org entries referring to line 738

View Material Textual Note for 734
734O Hamlet, what <a> falling off was there 

View Commentary Note for 738
738 Vppon a wretch whose naturall gifts were poore,1.5.51

View Immaterial Textual Note for 738
738 Vppon a wretch whose naturall gifts were poore,1.5.51

View Material Textual Note for 738
738 Vppon a wretch whose naturall gifts were poore,1.5.51