Posting the Sears 917.xxxxxx would allow one to look at the correct schematic.
Looking at "a schematic" for a DGS 6500, the PTO is wired-
A1 terminal of the key switch, through the PTO switch, to the PTO.
Check the connector to the PTO switch for tightness first. You might unplug/plug a few times to clean contacts.
It's a RED wire all the way through to the PTO.
Did you check the voltage of the RED wire (at the PTO connector) to ground, NOT the other black wire?
You might also check the BLACK wire at the connector for continuity to GROUND.
Looking at "a schematic" for a DGS 6500, the PTO is wired-
A1 terminal of the key switch, through the PTO switch, to the PTO.
Check the connector to the PTO switch for tightness first. You might unplug/plug a few times to clean contacts.
It's a RED wire all the way through to the PTO.
Did you check the voltage of the RED wire (at the PTO connector) to ground, NOT the other black wire?
You might also check the BLACK wire at the connector for continuity to GROUND.