Help! Intermit. starting problem!!

OK, I'll try to be breif.. 1967 Dart with a 1970 318.
What is happening; sometimes I turn key and it start to click and turn engine and then it stops, I turn back off and turn key back "ON" and gadges show power applied, turn further and nothing, leave power on and short starter relay with screwdriver and it starts right up.
Things replaced or have done;
Starter, Starter Relay (Twice), Ballast Resister, Pos & Neg Cables, Ignition switch and tumbler (I needed new keys!) Today I took relay off of fender and sanded paint off of mounting position and put electrolite gel for contacts and reinstalled thinking this would take car of bad ground.
It still happens, even after fully charging battery.
HELP!!!! Anyone???? I would shoot it but it the wifes daily driver!