Three years ago I had some time on my hands and wrote some utilities to help me sort out the pile of .d88s that I have. These were then forgotten, but I have had a few days to muck about with them and have tried to polish them a bit. They are to be regarded as beta, please, and I am unlikely to have time to fix anything major. I am just an occasional hobbyist programmer. So, use at your own risk, and PLEASE don't expect rapid bug fixes.
The basis for them is the file spec kindly provided by Ashura on the Tokugawa Corporate Forums, without which nothing would have happened. Thank you Ashura!
The general idea is to read the .d88 header, follow the tracks, read in the sectors, and then to compare the concatenated data given in the sectors according to the sector headers, with the track itself. If these are not the same, there may be something wrong, or not, depending, but at least you can see where there might be an issue.
.d88s are funny things, and there are some weird ones out there, and ones that aren't quite consistent with the specification, but will still work. I have tried to accommodate some funnies, but if the file is too funny or corrupt, the utilities just won't load them.
Note that the programs each have a "Libs" folder that must be present in the program folder. Otherwise not working.
You can leave me ( peter_j ) a pm on the Tokugawa forum.