You have the Label Length command set to 500 (LL500) which is 2.5". Change it to 160 and it should give you the 0.75" you want.
Mark
^XA^MMC^MNN^MTT^PON^PMN^JMA^PR4,4^JUS^CI0^XZ
^XA
^LH0,0^LL160
^BY2,3,70^FT425,100^B3N,N,,N,N
^FD12345^FS
^FO400,110^A0N25,25
^FDCEMVAR1000X1000X20004FLHS^FS...