Good ML monitor I can stick in a 2001-N ROM for debugging?

I have a nice graphical clock app I wrote that works perfectly in VICE, of course, but not on the real PET when I flash it into a ROM and try to run it that way. Using the really basic monitor in the PET I can verify the code's there but that's about it.

Most likely i have things like inline data that are now ROM and fail, so I can probably just fix it by hand, but still... it'd be nice to have a basic disassembler in ROM.

Is there one out there? I saw NEWTIM but (a) it said CBM30XX series, and mines a PET2001N. It also appeared to be german, not ideal.

Any pointers would be appreciated!

Thanks,
Dave