So I have made a bit of progress. The flash keeps dying at cmt-mcusw. From doing a search noticed that the only items left after cmt-mcusw was the kernel and rootfs. So I extracted the pr1.3 image:

flasher-3.5 -u RX-51_2009SE_20.2010.36-2.002_PR_COMBINED_002_ARM.bin

then manually installed the kernel with

flasher-3.5 -k zImage -f

and then finally rootfs

flasher-3.5 -r rootfs-jffs2 -f -R

Both installed with no errors. The phone started up fine with the new flash. The only things I noticed was when Settings...About Nokia was selected the settings panel would shut down with an error and the Nokia information screen in Settings shows the version as <unknown>. I tried to flash again using the full bin image but it died again at cmt-mcusw. Question what does cmt-mcusw do, how can I get it installed?