Intermittent Starter issues

[ddesocio]

Good Morning
I have a 59' Fiat 1200 TV and I have had the starter rebuilt 3 times at this point and the repair place cannot find anything wrong. It bench tests just fine and plenty of torque. I did a few voltage drop tests that he suggested and all looks good. When I hit the pushbutton on the dash and all is working properly it starts quickly. Then at times it is completely dead - nothing. I replaced the ground strap, battery cable. The only wire I did not replace is the brown wire from the starter to the ignition switch. It looks fine but original and a bit brittle.
Any suggestions will be greatly appreciated! Thank you in advance.

[Nut124]

When this happens, have you checked if there is 12VDC at the start button?

If the button gets it's 12V from the ignition switch, next time, tap the ign switch with a screwdriver handle to see if the ign switch is bad.