Ap3g1-k9w7-tar.152-2.jb.tar

tar -xvf ap3g1-k9w7-tar.152-2.jb.tar # Result: ap3g1-k9w7-mx.152-2.jb (the main image) Then TFTP the .mx file to the AP in recovery mode (AP button pressed during boot to get switch: prompt).