If a glyph that has components changes location in the 'glyf' table is there any other table that has to change as well, *other than* the 'loca' (and 'glyf') table. In modifying glyphs in the glyf table, I update the loca table to account for the changed size of the glyphs and it all works fine, *unless* there are component glyphs (as opposed to only contour-basd glyphs). If its just contour-based glyphs everything works. As to what exactly the problem is, i don't know yet - various utilities are rejecting the font file without useful explanation. As for now, I'm just changing the contour glyphs and writing the compound glyphs back unchanged (and updating the loca table) and even that doesn't work.