I finished!
Orion Pimpdaddy wrote:I was busy mapping The Machine, pausing and drawing, and after a while I found myself farther into than I had ever been. I thought this was going to be it, the time when I finally put this meat grinder behind me. Well, then a power surge happened and the lights flickered in my house for a couple of seconds. It reset the Sega CD!

The Machine is the hardest by a good margin (Dark Water in Genesis is also very harsh as it has enough insta-kills by crushing in a long level, and then the boss fight without a checkpoint... In Sega CD The Machine is easily the hardest by far). You don't seem to need tips but here goes for others.
Once again, regular sonar can kill stuff just fine, don't bother sonar charge. Only rarely you will need to actually use the C button swim. D-pad should be enough. In most of the level you will do well by swimming in circles and spamming sonar machine-gun style in all directions. That is enough to kill the enemies well before they touch you the vast majority of the time. If the head is still alive they will keep harassing you and can easily kill you if you let them.
The worse is not the enemies (after you are used to them - the above circling tactic helps). You will die the vast majority of times by being crushed (either because you got trapped due to the scrolling or because you have a hard time navigating.
After a while you will rarely die from navigating. You get a bit used to the navigation style which is after all similar to the Tube as well.
The worse is In some parts of the level (I'm afraid you will have to memorize a bit or map it) there are "traps" to crush you where you need to be on your toes and swim through a narrow part and sort of already know where the scrolling will go next. There are about 3 parts in the level where I think that even a very skilled navigator will hardly make it the first time.
After all that the last boss fight is easy by comparison. You really don't need to die in this one unless you try to be a hero and "speed run it". You regen - the enemy doesn't. Take your time and play carefully here and you can clear it on the first time if you can figure out what to do (it is more obvious than the other boss fight).
Ivo.