Cannot Get This Lisp To Work on All Blocks in a DWG

We are trying to write a lisp that will set all blocks in a dwg to an X, Y, and Z scale value of 1.

By my reckoning it should work. But it only applies the scale change to one block in the dwg - the latest one that was inserted.

Do I need to loop through the selection set? I assumed it would apply the change to all in the selection automatically.

Thanks for any help. See below for code, and see attached a sample dwg that shows one block only changing.

(defun c:SCB ()
 ;(setvar "qaflags" 1)
;below selects all blocks 
 (setq ALLBLOCKS (ssget "X" (LIST (cons 0 "INSERT"))))
 ;(command "select" allblocks))
 (if  
       (progn
       (setq blocks (ssname ALLBLOCKS 0))
               (entmod ; modifies the properties of the entity
                   (append ; combines the list
                       (entget blocks); indicates what entity to edit
                       (list ; create a list of properties to change
                           (cons 41 1)
                           (cons 42 1)
               (cons 43 1)
                       )
                   )
               )
                   (entupd blocks); updates the block
       )
       (prompt "\nNo blocks in drawing!")
  )
 (princ)
 ;(setvar "qaflags" 0)
)

16-027Hkjkl.dwg

Yes, of course you need to loop over the selection set. Plenty of examples out there. Just search.

Heres a handy tutorial about how to iterate through a seleciton set.

Try this

;below selects all blocks 
(setq ALLBLOCKS (ssget "X" (LIST (cons 0 "INSERT"))))
 ;(command "select" allblocks))
(if  
       (progn
       (repeat (setq x (sslength allblocks))) 
       (setq blocks (ssname ALLBLOCKS (setq x (- x 1))))
               (entmod ; modifies the properties of the entity
                   (append ; combines the list
                       (entget blocks); indicates what entity to edit
                       (list ; create a list of properties to change
                           (cons 41 1)
                           (cons 42 1)
                           (cons 43 1)
                       )
                   )
               )
               (entupd blocks); updates the block
       ) 
       ) ; repeat ?
       (prompt "\nNo blocks in drawing!")
  ) ; progn
 (princ)
 ;(setvar "qaflags" 0)
) ; if 

Its just me but I put ) ; if its so I can keep track of the closing pairs makes it easier to add to code like this.

Thanks BigAl, was able to put something together from your comment and the tutorial above.