When to change a motor along with a capacitor?

So, I've been called for help by a friend who needed me to check out why his Condensing Unit keep coming on and turning back off. When I get there, I found his fan wasn't spinning. I popped off the door then found a snake fried on top of the condenser. I told my friend he would need a capacitor and a motor. Most the time I went along with service guys in my company, we usually change out both. Well my friend went along and got a "Second Opinion". That guy told him forget buying the motor. -Can someone tell me in what conditions does both need to be changed and when not? I won't leave this post up for more than a week because I know Capacitors is a #1 issue in the HVAC field? I just need some education on this.

Can someone tell me in what conditions does both need to be changed and when not?

It's only necessary to change both when they're both bad. Replacing just the capacitor first will most likely save a bunch of money. Electrolytic capacitors especially don't handle sudden extreme discharges well & it sounds like the snake provided that opportunity.