"The one thing I notice about "reverse mode" is that the blades don't stop when I get off the seat like they do when I'm in "forward mode"
The blades should stop if you get out of the seat with it in "reverse mode". So this might be more info to point to an issue with the reverse switch. You need to locate that switch and test it with an ohm meter and make sure the wires and connector are good. There's plenty of youtubes on how to locate and diagnose a bad reverse switch so you might take a look. Cheers.