My truck is hard to start?

So, I just bought this truck and when you go to crank the truck and turn the key to the run position it’s trying to crank and takes like 6 or 7 tries before it starts. I have taken the ignition switch out to illuminate the ignition lock and it still does it. I have tried putting it in neutral and it will work how it’s supposed to, but you can’t turn it to the start position. Would you maybe have a solution on things to check? The previous owner said he changed the ignition housing and that’s when it apparently started doing it. Please help. I don’t want to burn my starter up.