Thats a big 10-4 on not getting it stripped properly whoever did it. If at all, it looks like they just laid finish on top of it. I would take your 175 and put a High Performance Black pad on it. Your going to need a good stripper. Might have to strip 3 or 4 times to get all the way off. I like Buckeye's Juggernaut ultimate cold water stripper. Assuming you have a shovel nose to pick up the stripper, if not your going to need a good squeegee and shopvac.
More than likely whoever stripped it didnt scrub the floor and just mopped on the stripper. Those dark spots are the areas where the old finish is at, which is helpful for you to see before you start. Once you restrip, probably twice, clean and scrub again with plain water before nuetralizing. Afterwords, mop the floor with a neutral cleaner. Look at the floor from a distance and if you see the dark spots while the floor is still wet, then you know that is where you have leftover stripper that still needs removed. Whatever the floor looks like when its wet is what it will look like when your finished with the finish application.
I used to work nights at a hospital in the medical records and I spent untold hours in the archives pulling research charts..anyways they always do janitor stuff at night and one week they were stripping the vct and every night more layers were stripped off and it looked exactly like your picture but without the new wax..so my point is I've seen proper strip and wax of vct and this picture is as if someone got lazy and decided the hell with this, the old wax is taking too much time to strip off and put down new wax hoping no one would notice or care.
I have seen jobs like this too many times living in a town with a Johnsons distributor. Do a test spot BEFORE you commit to the job. Sometimes it is crappy designed floor sealer like a product from Johnsons called Technique. That stuff is next to impossible to remove because it was designed to not be removed with stripping procedures. The moron chemists there thought it would be a great idea to have permanent protection on the vct from the stripper solutions. (??)
Problem is the sealer yellows/darkens over time and the poor fella that has to strip it ends up with a floor that looks a lot like your photos. Traffic/abrasion wears down some areas and these strip off but what gets left behind is ugly. Don't always assume it is the previous floor guy that did a poor job.
Get you a stripper that has a good amount of benzyl alcohol in it. It will melt through urethane fortified finishes and sealers and simply tear through acrylic finishes. Apply to the floor and let it dwell for 15 minutes. Dont even agitate, just keep the floor uniformly covered. Pick up the solution quickly without agitating with a front squeegee mounted wet vac or similar but immediately apply a second round of stripper right behind that before it has a chance to dry. Let it dwell again then this time agitate and pickup.
Whoever cleaned it before , made a half assed effort to strip.
Probably used a short dwell and the wrong pad.
This will be an easy job.
Those greyed out areas will come out like new with stripper and a black pad.