
Originally Posted by
artisteroi
first save as a new file
use the quick select to select all instances of the block, go to edit menu, copy with base point, 0,0 enter.
now delete the selction of blocks. they no longer exist in model space. There is still an instance in the database however.
open the block editor and browse the window to the block you want. make the changes you want in the editor and save the block and close the editor.
now go back to the edit menu and paste, insertion point 0,0. cad will get the new block definition from the database to re-insert the items. it will ask you "redefine the block" say yes. you should now have the new block modified for all instances.
this can tax the database, so make sure you save first. if the file is very large it can cause memory problems. you still have to wait for it to update but since you are already in model space there shouldn't be problems with the drawing coming back. good luck