It is the small lever to the right of and under the "dash" that otherwise locks and unlocks the quick-attach mechanism.
After mounting and locking the mini-hoe attachment you unplug the hyd hoses from the locking mechanism and hook them to the hoe. This is the circuit that opperates any attachment that uses a hydraulic cylinder rather than a motor.
Back in October of '03 "mckat" posted a slick and simple way to extend this control lever function to the upper left side of the dash. Check the archives under "Mods or custom attachments".
On my PT-1845 I drilled a hole above the valve and fabricated a new lever assembly on top between the dash console and the existing joy stick. Could be a tighter fit on a 425 though.
Rip