Giving A/C start capacitor replacement a try

Yup I had a capacitor go bad on a unit once. They wanted $150 for a capacitor + install. I got one through Amazon for $17 shipped next day. Been working like a champ.

I'm working on our older Mach3+ right now so I could go right to the parts listing with your model number. We both have: 7.5mfd Fan Run Cap and 40mfd Compressor Run Cap. Ours has a Start Capacitor and a Start Relay. Yours has a Start Capacitor with included PTCR device. Relay and PTCR both serve to take the Start Cap out of the circuit once the compressor gets up close to operating RPM.
So, your 40mfd capacitor and/or Start Kit could be bad. It needs both to start then run. That's assuming something else isn't the problem.
Do you have a way to test capacitors (DVOM with mfd capability)? To test for Current Draw (clamp-on AC ammeter)? If so, you can narrow it down.
Our unit does NOT have the compressor start delay that you mentioned. When you say "doesn't even try" have you been able to determine that power is being sent to your compressor?

I ordered the complete 40mfd start capacitor with the PTCR device. I have voltage on the load side of the breaker and at the top unit. I'll put the amp meter on tomorrow and see if I get any current draw.