Power turns on but it won't turn over

[mckiller1195]

I just recently bought a 85 ranger up until now it would start up perfectly fine with no issues but after replacing spark plugs the power will turn on but it won't engage the starter I've replaced the starter solenoid and the ignition switch and nothing has worked it will still start if you trip both sides of the solenoid with a screwdriver or something of the sort but I'm at a loss for what to check next