Craftsman 917.272264 Electrical Issue - Will Not Start

I have a Craftsman 917.272264 that will not start. I bought it about 3 years ago and it was having intermittent issues with not starting from the ignition switch. I noticed the wire connectors on the switch were very corroded so I replaced those. Still didn't work. Next I checked the ignition switch itself with my multimeter. It was bad so I just replaced it. The hours meter will activate when in the On position but I will not engage the started. I just replaced the solenoid but still no luck. It will start if I put the key in the On position and jump it directly on the starter from my car. Any thoughts on what it could be? I have attached the schematic

This procedure may help you troubleshoot your problem.
[FONT=&quot][FONT=&quot]Electrical* problems can be very easy or very difficult, depending on four things.[/FONT][/FONT]
[FONT=&quot][FONT=&quot]1. * How well you understand basic electricity.[/FONT][/FONT]
[FONT=&quot][FONT=&quot]2. *What tools you have and know how to use.[/FONT][/FONT]
[FONT=&quot][FONT=&quot]3. *How well you follow directions.[/FONT][/FONT]
[FONT=&quot][FONT=&quot]4. *You don't overlook or assume anything and verify everything.[/FONT][/FONT]
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[FONT=&quot][FONT=&quot]Remember we cannot see what you are doing. *You are our eyes, ears and fingers in solving this problem. *You must be as accurate as you can when you report back. *The two basic tools we will ask you to use are a test light and a multi-meter. *If you have an assistant when going through these tests it would be very helpful. *These steps work the best when done in order, so please don't jump around. *Now let's solve this problem.[/FONT][/FONT]
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[FONT=&quot][FONT=&quot]First, check the fuse(s), check battery connections for corrosion (clean if necessary) and *voltage - above 12.5 volts should be good.*[/FONT][/FONT]
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[FONT=&quot][FONT=&quot]Second, check for power from the battery to one of the large terminals on the solenoid. *One of the wires is connected directly to the battery and has power all the time so one of the large terminals should light a test light or show 12 volts on a meter at all times.*[/FONT][/FONT]
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[FONT=&quot][FONT=&quot]Third, *check for power at the small terminal of the solenoid while depressing the clutch/brake pedal and holding the key in the start position (you may need an assistant to sit in the seat to override the safety switch). If your solenoid is a four wire solenoid, check both small wire terminals as one is ground and the other is power from the ignition switch. *If your solenoid is a three wire solenoid, make sure the solenoid body is not corroded where it bolts to the chassis of the mower as this is your ground path back to the battery. *If in doubt, remove the solenoid and clean the mounting area down to bare metal. *If there is no power to the small terminal then your problem is most likely a safety switch, ignition switch or in the wiring.*[/FONT][/FONT]
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[FONT=&quot][FONT=&quot]Fourth, check for power on the other large terminal of the solenoid while holding the key in the start position q(you may need an assistant to sit in the seat to override the safety switch).*[/FONT][/FONT]
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[FONT=&quot][FONT=&quot]Fifth, check for power at the starter while holding the key in the start position (assistant again).*[/FONT][/FONT]
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[FONT=&quot][FONT=&quot]Sixth, check your ground circuit back to the battery.[/FONT][/FONT]
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[FONT=&quot][FONT=&quot]After you have gone through each of the above steps, let us know what happened when you did each step. *At that point we will have great info to tell you how to proceed. *Remember you are our eyes, ears, and fingers, so please be as accurate as possible.[/FONT][/FONT]
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[FONT=&quot][FONT=&quot]Be as specific as possible with voltage readings as this will help diagnose your problem quicker. *If you do not know how to perform the above checks, just ask and I will try to guide you through it. *Youtube also has some videos and as you know a picture is worth a thousand words.[/FONT][/FONT]

Thanks for the guidance Rivets, will do!

Followed the steps you outlined and I’m not getting any power on the small posts of the solenoid. I checked the interlock switch for continuity and it was fine. The seat switch is functioning properly as well. I jumped it directly at the starter and it’s working. Im at a loss where to go next. As I was using it yesterday I blew the pto switch. I am not getting proper continuity as indicated in the scematic. My concern is I am not sure if this could be a source of the start failure. I would hate to throw more money and time into the this mower but I really can’t afford a new one