A plaintive wail from the darkness... My SL-15 just went on strike.

This ancient SL-15 with Fanuc F10T9B controller just stopped working. It was running fine when I left yesterday, but on the night shift it just... stopped, apparently.
To be clear, I'm not a CNC guy. I'm a millwright who has this lathe to make small parts once every few months.
When I arrived it had the parts-counter screen up (I have no idea how to get to it manually and have never intentionally set anything on it before today) and it showed the same number of parts made as the counter was set for. This has never happened before. We have made thousands of small parts on this lathe and have never hit a counter. This was a run of 1,500 parts, but we have done a run of 10,000 parts before.
Since the page was on the screen I tried altering the values to zero to re-set it. It seemed to accept the values that I entered, but after entering the values I couldn't get the screen to go away. I ended up having to turn the controller off and back on again. I re-zeroed the lathe and hit the green button. Nothing. The machine will jog manually and change tools with no trouble. It clamps and unclamps the 3-jaw chuck and the green light is on indicating the chuck is closed.
It won't run on automatic. It was running yesterday.
I tried shutting it down for a longer period, but that didn't help.
I have a full manual set (not cheap!) so I tried looking up the parts counter, but as has been my experience before what little information is in there is of no use on my ancient controller. The manual says the values are on the Settings/Handy screen, but they aren't there for me. The manual says it won't show up unless you're in the right mode, so I tried EDT,MEM,and MDI and in none of those modes do the counter variables show up on the screen.
I am *assuming* that the problem relates to the parts counter, but I don't actually know that to be true.


Any thoughts?

Update:
I have more time to look at it today.
I have verified that *everything* I can think of works except for automatic mode. I can zero it, jog it, change tools, and run the spindle.

I opened the cabinet to check the master PCB, and it shows a green light and a "1" on the LED, so it seems to be happy.

When I open up the diagnosis screen I can see that the E-stop is bit #1, and when hit it wipes out the next six or so bits. It triggers and releases as expected.
The third bit is the stop button (normally closed) and it activates normally. The start button I would expect to be bit #2 but it does not show up anywhere when I press it. At first I thought the button was bad but I have verified with a meter that it closes.

The status line on the CRT shows the mode (MDI,MEM, EDT, whatever) and then there are three asterixes, then STOP, then asterixes until the end. No other status info.

I pulled up the 1000 byte in the diagnosis info and it is all zeroes. Not waiting for anything... no background tasks. Same with the 1001 byte.
The 1010 byte shows all zeroes.

So as far as I can tell the machine is happy, but it just doesn't want to run in automatic. I'm still digging, but any info any of you more experienced folks want to send my way would be greatly appreciated.

Another update.
I don't seem to be getting a lot of traction with this problem, but I'm going to keep updating it in case it is of use to someone else in the future.

Everything that I can find indicates that the machine seems perfectly happy and is ready to run... it just won't do it.
The fact that the cycle start button is not showing up in the diagnosis page makes me hope that this is an electrical issue, not a software issue.

The cycle start button takes it power from the 24NC rail, and returns it on a wire labelled STM. I was hoping that wire would go through a few switches and sensors before reaching the main PCB, but unfortunately it does not. (according to the wiring diagram). I am going to cut the cable ties so that I can manually trace the wire all of the way back, and see if the signal is making it to the main PCB, or if there is a wiring problem somewhere in between.


Okay, I had forgotten hit 'send' on this, and I have done a bunch more work. I am now confident that the signal is getting through, but it is being ignored for some reason.
I have been going through the ladder logic and I found page 20, which has some VERY tasty tidbits, indeed.
I don't see a way to upload pictures, so I will have to just describe a few things.

Firstly, in the drawings Xn.n are manual push buttons. Rn.n are memory values.
Page 20 shows us how the physical cycle start button sets two memory values R6.3 and R6.4, but then we have lines of STARTOK stuff, and I think THIS is where the answer is.
What I need now is to know how to view these memory locations so that I can see why the ladder logic is not completing.
Is there a way to decode which of the values on the diagnosis screen are which Rn.n values?

Got it fixed. The tailstock (that I never used) was a hair out of position and it was interlocking the automatic mode.