> od -A d -t x1 vmlinuz | grep '1f 8b 08 00' 0024576 24 26 27 00 ae 21 16 00 1f 8b 08 00 7f 2f 6b 45

so the image begins at 24576+8 ⇒ 24584 . Then just copy the image from the point and decompress it -

>dd if=vmlinuz bs=1 skip=24584 | zcat > vmlinux 1450414+0 records in 1450414+0 records out 1450414 bytes (1.5 MB) copied, 6.78127 s, 214 kB/s