[FlatheadTed]

If can be many things but as suggested wire and alligator clips top of list , On a day out my 35 Coup had to be push started , as soon as I got back to the shop I hot wired it and it started right up after investigating I found a loose wire on the back of the switch ,the stud was not threaded right up ,for the sake of a little split washer .So voltage drop when hot ,