It seems Ian is one of those that thinks if you don't do it his way, he gets rude and condescending about it!   If you think his advice makes any sense, go for it!  We have the throw-out bearings in stock, cheap and (relatively)easy to change:

//www.minimania.com/part/GRB201/Clutch-Release-Throw-Out-Bearing-Pre-verto-Mini--Coopers

Thousands of people have seen my very simple clutch adjustment video, on my own car, from several years ago.... still works the same, not adjusted it in years!....but I am happy to sell you a throw-out bearing every month!

Can't do much about the crappy heat-treating of the thrust plate, but it is 100% certain that it will last WAY longer if properly adjusted, and not grinding on that spot whenever the engine is running.... Your off-center wobble is caused by gravity!  When the pressure plate is bolted up with the engine upright, it's very easy to allow it is to "sag" off-center!  When you bolt up the straps that way, it won't quite self-center!  On an engine stand, you point the crank straight up and get the clutch on nicely centered!  Of course you can pay attention to that and get it right, but it's not that obvious to people!   If you have old diaphragm pressure plates around, by all means do the 'file test' and use the hard one!  Easy to swap that thrust plate.

I've expereienced that same wear.
Also a very worn pin

sarch3134: you now say the slave cylinder isn't moving the lever and the lever has tolerance.

Can you manually pull the lever (with another tool if needed) and depress the pressure plate? If not, your problem may be in the clutch cover end - broken or worn lever, jammed plunger, displaced throw-out etc.

If that end is ok, bleed the slave to see if fluid is actually moving - the hose may have collapsed internally, blocking the fluid.

Try a file on that thrust plate. It should be hardened, and I bet it's not. Seen it many times.

There were a whole lot of AP brand clutch diaphragms sold with soft thrust plates, they wear just like that, I have bought 3 new orange dots in the last 3 years with soft plates.
Don't blame the bearing or adjustment.

Cure- toss that plate and fit one from an old diaphragm. Better fit a new bearing too as it's apart.

Ok, I went out this morning to do some research and I had no clutch. The pedal was unresponsive and I think the slave cylinder has gone bad. It only pushes ever so slightly on the clutch arm (until there is risitance) then it stops. I looked through the viewing window and it is not moving the diaphragm. I went ahead and topped off the clutch fluid and bleed it but did not gain anything.

I am curious now if that sound was coming from the failure of the slave cylinder. Maybe some bearing gutter/clutch slippage due to not having full range to disengage? Well I will approach this again in a couple of weeks when I get my parts in to fix the slave. 

On a side note I went ahead and check and there is some slack between the clutch arm and the set screw under it. I also have a spring, went ahead and put it in after the rebuild since it was not present when I purchased the car. 

I'd lean more toward Jamal's advice and ensuring the return spring is in place. (Jamal does know what he's doing, or he wouldn't be working at MiniMania I think.)

The stop bolt takes the extra slack out of the lever-plunger-throwout- diaphragm linkage, but it has a tolerance setting to leave SOME clearance. The spring holds the lever - and any slight pressure coming from the other half of the system (pedal weight, master cylinder, fluid, slave cylinder) away from the plunger. As Ian suggests his might not be a problem for many cars, but that is how it was designed. The pre-verto release was not designed to spin constantly. When released it would be pushed just clear (something like disk brake pads do.)
If you had any residual pressure on the release bearing, it would remain in contact with the diaphragm, spin, warm up, expand, get hotter, be under constant pressure and cook itself.

The "off-centre" scorch/scrape may be the result of an old release bearing getting chewed up, or maybe it was sagging if the tolerance of its support on the plunger wasn't right. Check that too.

If that's his advice I'd be avoiding any such video like the plague...

The "stop bolt" - whatever that is - has no influence whatever on the bearing.  I say that because there is no bolt that holds the bearing off the plate.  The return spring does this but is not really necessary.  I don't know anyone who's dropped the spring who has had problems. Certainly not me. Unless its under constant load it will spin happily for years.

The wear on the diaphragm is consistent with a cheap diaphragm.  A good quality one will have a hardened plate that the bearing won't damage. You won't be able to mark a good one with a file... I usually swap the proper old plate onto a new diaphragm just in case.  But the worn plate is really a consequence rather than a cause ..... 

Its difficult to do remote diagnosis but I would almost agree with Jemal that your clutch may not be adjusted properly.  But its the opposite of his suggestion.  If there is NOT a gap between the adjusted bolt and the clutch arm then the release bearing will be under constant load ..which will wear it prematurely and, as it stops spinning freely, it will grind against the diaphragm plate eventually causing damage consistent with your photo.

But then, maybe you just got a defective/ inadequate bearing in the first place... ???

Cheers, Ian

Another thing to watch is that bearing plate, the newer after market stuff use a softer metal/hardening and they will wear even if the clutch is properly adjusted as Jamel states.

You clutch is not adjusted properly... you have a constant load on that bearing because your 'stop bolt' in the housing is not holding the bearing off the spinning clutch assembly.  Many people will tell you to run without a return spring and just let the bearing "rest" on the pad where you see the wear.  That throwout bearing is not designed to run at engine rpm non-stop and will scorch itself quickly if set up that way. I've put up a video showing proper adjustment several times.... Search for "clutch adjustment" or just my name "Jemal".

Thanks for the help on uploading the image! I don't know how I missed that 

There's a green image uploading button above and left of the area you type in your message.

The release bearing in my classic mini (pre-verto clutch) is going out, currently making a whirling metallic noise when the clutch is depressed... The clutch was just overhauled 500 miles ago. Including the ring-gear, release (throw-out) bearing, diaphragm, and the clutch plate itself. The old diaphragm was being scrapped by the old bearings, and looks a bit off center which makes me think the issue is larger than what I know about this clutch system. The image of the old diaphragm is attached. 

Is it possible that something was not installed correctly during the replacement? Or do you think I have a bad bearing set?

I don't want to replace the release bearings every 500 miles, any help would be great!