Help needed to get my 7i76E + 7i85S + 7i73 on my mill going.

I thought so too, there is no real hurry when the wrong gear is detected.
Rod, I think that will be your challenge to do right-gear-detection in hal.
I have no clue on how to do it. Except to replicate the C code in hal, kind of.

I think the loop doesn't even take 1 microsecond to execute. After all, the processor
runs at the GHz level and even with some overhead 1 microsecond is a long time.

But any right-gear-detection routine would work I guess.

Regarding the notification to change gear, maybe
halui.mdi-command-00 can be used?

Not sure if the command can be as simple as
(MSG, Change gear, tecno!)

Could it be possible to have a 'tab' in gmoccapy with leds for each gear?
This 'tab' to be called up each time Sxxxx command is issued.

Wanted gear combination flashing and actual if wrong in red and green if correct?

Just an idea but how to make this future proof for new version of gmoccapy?

Have a look at the tutorial linuxcnc.org/docs/html/gui/gladevcp.html...th_the_example_panel

I think this is not far from what you want to do.
You can start from one of the examples and add LEDs for your gear indicator.

Well to have gears and leds seems pretty straight forward but how to read Sxxxx and translate that to gears needed?

I actually don't know but I can guess

The gearblocker component finds out the gear you should use (the for loop we don't talk too much about )
The gear you need is an "int pin". It must be possible to get the int from that pin into the glade view. "Must" as in "I guess".