Mortise lock part ID

[hjlocks]

Hello all,

Hopefully someone can identify the part I'm looking for as searching by a description doesn't seem to be working. I'm looking for piece for a 65+ year old residential mortise lock that mounts in where a mortise cylinder would normally screw in, but acts as an actuator for a thumb turn.

The thumb turn is nearly identical to this one http://www.houseofantiquehardware.com/v ... turn-brass

The piece I'm looking for can be seen in this photo in the bottom left part of the case.
http://www.mikedidonato.com/images/2009/04/mortise3.PNG

Additionally I could use a good source for spare parts for older mortise hardware. There's a Baldwin distribution center in town, but they don't have much in compatible parts.

[dll932]

That is called a thumbturn cam or turn knob disc.

http://littlegreta.ecrater.com/p/163029 ... b-deadbolt
http://locksmithtoolandsupply.com/PDF_C ... 20Pins.pdf
(turn knob disc page 6)
http://www.progressivehardware.net/mortiselock.html

Note that they are spring loaded to return to the horizontal position as in the pictures. If the spring is broken, the piece can go vertical, jamming the bolt from outside.