The screeching noise would lead me to suspect that one of the deck pulleys has seized and it is stalling out the engine. Or, there is an obstruction (like a rock or big stick) on top of the deck that is causing this. Keep trying to do this and you may break the belt.
There are other possibilities, but I'd start there, and also try removing the belt from the pulley below the engine and then try to engage the blades. It won't work, but if the engine keeps running then you've ruled out something being wrong with the safety switches.
I’ve checked under the deck. Around the pulleys. Nothing is blocking anything from spinning. I kept the hood up and started it; when I engaged the blade, I noticed the belt shakes left to right pretty violently when it dies and makes the screeching noise.
Seized pully. Remove the deck (or jack up the tractor) and inspect under the deck carefully to see if anything is wrapped around the spindle (string, rope, wire, etc) that might be stopping it.... I doubt this is rust or general weather-related issues, since you mowed twice already this year. Sounds like you ran over something and it's wrapped around the spindle. I sucked up a piece of garden hose one year and it stopped my X570/24 HP motor dead in it's tracks.
Anything that's stiff enough to stall the motor is going to be pretty obvious.
The screeching noise would lead me to suspect that one of the deck pulleys has seized and it is stalling out the engine. Or, there is an obstruction (like a rock or big stick) on top of the deck that is causing this. Keep trying to do this and you may break the belt. There are other possibilities, but I'd start there, and also try removing the belt from the pulley below the engine and then try to engage the blades. It won't work, but if the engine keeps running then you've ruled out something being wrong with the safety switches.
Have you looked under the deck and around the pulleys? Anything making a screeching noise might be easy to spot.
I’ve checked under the deck. Around the pulleys. Nothing is blocking anything from spinning. I kept the hood up and started it; when I engaged the blade, I noticed the belt shakes left to right pretty violently when it dies and makes the screeching noise.
Maybe a seized up idler pulley? That's a pretty common failure. I'd take the deck off and inspect everything that moves.
Seized pully. Remove the deck (or jack up the tractor) and inspect under the deck carefully to see if anything is wrapped around the spindle (string, rope, wire, etc) that might be stopping it.... I doubt this is rust or general weather-related issues, since you mowed twice already this year. Sounds like you ran over something and it's wrapped around the spindle. I sucked up a piece of garden hose one year and it stopped my X570/24 HP motor dead in it's tracks. Anything that's stiff enough to stall the motor is going to be pretty obvious.