860 won't restart

1955 Ford 860 converted to 12 volt negative ground. Ignition switch fell apart a few weeks ago so I bypassed it and used the tractor for 4 or 5 hours. Picked up a cheap ignition switch the following week, installed it and she fired right up. Ran it for a little while as I switched the blade out for a pond scoop.Drove it to the creek to move some rock, and it died, like someone turned it off. Cussed myself for buying cheap parts and bypassed the new switch and no start.Made sure gas was on, pulled bolt out of float bowl, seems to have plenty, clean, no water. Grabbed digital multi meter. I should mention I have no electrical training. I have 12.4 volts at battery and same out of ignition switch to resistor. Same voltage from top of resistor to positive side of coil. Pulled coil wire from distributor cap, checked for spark, saw done.12.4 volts to negative side of coil, and from there to the bottom of the distributor.The connection there, where it goes through the side of the distributor seems to be insulated. Cleaned points with 400 sandpaper and re-gapped to .025.Have continuity on points when closed. All connections are bright and tight.Pulled #4 plug wire, stuck in an old sparkplug to check for spark, saw nothing.Getting ready to go to town and get another set of points and a condenser, and maybe a 12 volt test light. It'll be about 90 miles round trip, so might get a coil while there. What am I missing?
Thank you,
Gary

Sand paper leaves behind a bit of sand on the point so they cannot work as they should. Take a piece of card board like the flap off the box the point come in and use that to clean the point and then pull the center wire off the cap and check that you have a good blue/white spark that will jump a 1/4 inch gap or more

Thanks Old. I'll try that in the morning

check voltage at the points with the points open 12v closed 0

Tried rubbing it like Old suggested, didn't make any difference.
Gary

Sunbeam, I have 12 volts when the points are open and closed. I have continuity when points are closed but not when open. I'm really confused. Any suggestions?
Gary

When the points are closed it should be a dead short to ground 0 volts a points. Turn switch on take a screw driver and ark from points to distributor case see if you get a spark from the coil if so bad points

sunbeam- Could it be a 'shorted' wire going through the hole in the side of the distributer that comes from the coil. I've had that happen when a crack in the wire insulation occurs and shorts to distributer case.

If you had a shorted wire you would have no voltage to the points. It is possible that you have no ground to the points check for voltage points closed at the nonmoveing side of the points. If it shows voltage you have a bad ground.