Murray stalls when blades engage

[bertsmobile1]

IT is so much easier when people post proper details of their mowers from the first post.
The magneto kill wires are the yellow ones.
To kill the magneto the yellow wire goest to ground
This can happen either by the key switch connecting the yellow to ground
or
ground going through the seat switch then through the PTO switch then to the coil .
So you have either a short in the yellow wire between the seat switch plug & PTO plug
Or the PTO switch itself is grounding the yellow wire via an internal short .

 

[ben.cellamare]

Could the PTO switch ground itself via internal short and still show from the multimeter that it is in working condition? (via continuity) Also when I try to engage the blades the blades start to move but the motor just turns off.

 

[bertsmobile1]

Anything is possible
The safety circuit to protect idiot hands from being chopped off when they try to clean out a blocked chute with their fingers while the mower is running has 2 switches in it.
The seat switch & the PTO switch .
When the seat switch is in the "no one home position " and the PTO switch get put in the "chop your fingers off position " it grounds the coil & kills the engine or trips a relay & turns off the blades.