Intermittant won't turn over

I have a 2000 Nissan Frontier crew and once or twice a month I will turn the key to start yet nada. Everything else electrical works. Awhile back a friend installed a wire from the solinoid up to the battey. When it occurs I just turn the key to On and touch the wire to the battery and it will start. The solinoid has been replaced.

Any Ideas?

Thanks,
Bob