Hi LAN,

Yes John Stevenson is John S and that's who I was going to call on your behalf. If you speak to him again Mention Jazz was Kicking off again he'll laugh and call me not nice names which I can't say or they will be deemed OFFENSIVE . . LOL.!!

If you have a Galil card then I'd swap it in a heart beat as Galil is industrial strength Controller and will knock the spots of that AKZ250. Yes I agree you shouldn't have too but sometimes it's just easier to bite the bullet and get cutting reliably. Esp if you have such a quality Card already.!

The next best thing is sort the noise causing the issue. Debounce is a bodge to get you going. Removing the noise is the cure and easy enough done.
For a start check all the Grounds are correct with a Star setup and separate signal wires from Power wires. Often this will cure the problem if it doesn't then you'll maybe after look at other ways. Like Caps across the inputs. Thou to be honest I've never found them to work very well if noise is bad.

To test if it's noise thru the switch then just remove the E-stop and put a jumper across the inputs. If it does it again you'll know it's not the E-stop as it can't be noise on the e-stop line.
Personally I prefer 24V to run trhu my E-stop and controlling a Relay which shuts the machine down. The 5v input signal is then just run thru Relay contacts to inform Mach3 E-stop occured and with a very short wire run you'll never get noise on that input.