Bent distributor shaft?

[datzed]

I should also mention the ignition system has been replaced (plugs, leads, coil, dizzy cap and rotor, points etc etc) and the issue has been confirmed to be the shaft.

[GRN_VAGN]

well the shaft is connected to the oil pump from what i remember,
could be something out of alignment there, thats the only part that connects to shaft, besides the IM shaft.

[Stan]

dud spark plugs can do wierd things as well, seem perfect one time and crap the next.

Also if your dizzy has points and a condenser - little metal can on a wire, inside, a dud condenser can do this as well - when they get hot making an otherwise intermittant or no fault become obvious.

as for the bent shaft, it has to be hit by something, be up against something, or not inserted properly to bend. possible an output drive issue at the engine end...or alignment issue, not going in straight.