I had a similar issue on my John Deere yard tractor. In my case, the culprit was a loose/corroded blade plug on the seat safety switch. The PTO circuit usually has a couple safety switches that must be closed before it will engage. As a troubleshooting step you can try to jumper the switch connections, and engage the PTO. If it doesn’t die, you know it’s a bad switch. Like I said, mine was loose/corroded. Cleaning the plug contacts solved the PTO issue for me.
Hey Nick, You might want to check out Amazon and search for “locking tuners” under the musical instruments section. I found several options for locking tuner replacements there. Just be sure when you order to get a 6-inline pack, rather than a 3+3 pack. Hope that helps!
I was also unable to locate the replacement feet for that model. (Did you mean the 1100 Watt motor?) The service manual does list a customer service number, that might be your best bet. The Ninja customer support line listed in the manual: 1-877-646-5288 Good luck!
If I’m understanding your question correctly, it sounds like the behavior you describe is correct. The secondary function of the F-keys should work when pressed at the same time as the Fn key. For example, if you want to open a Help page in most applications, pressing F1 should work. However, if you wanted to Mute the audio, you would instead press Fn+F1.