if I create a TPT of 160 system and 2mb cache then it's fine. If I try and create a different system size (I've tried 165, 170, 175, 180) and do check image directory it lists appsboot.mbn and partition_zte.mbn as no match on the md5 check.
Using a gen 1 Blade TPT'd to gen 2 (which I selected as the model on first use)
What am I doing wrong?
You don't need to use the check image option after making a TPT with custom partition sizes. That option downloads the files, checks the md5sums and then edits those 2 to give the sizes you wanted. As they have been changed, the md5sums are different from those listed in the nandroid.md5 file, so they won't match anymore if you use check image. Once it tells you the TPT has been built, you can just start it from there.