MAFE lock mortice cylinder

[nite0wl]

An attendee at my local locksport meeting lent me an interesting lock that none of us had seen before. The face has the name "MAFE" stamped on it, seemingly the manufacturer/brand name. From the outside it doesn't look like much. The key is only cut for 5 pins and is shoulder stopped, the keyway is fairly wide and the warding barely qualifies for the most technical definition of 'paracentric'. Despite the apparent low difficulty of the design, it has managed to resist all of my attempts to pick it for the better part of a month now.

I discovered why it has been giving me so much trouble the other day when I gutted it to address a sticking pin.

The key pins are nothing special, they look similar to older CCL and Yale pins with blunted conical tips on the working end, you can see them sitting in their chambers in the plug on the left (the key is inserted and you may notice that the plug is tapped for 6 chambers, only 5 are used). The unique (at least to me) aspects of this design, and what has been torturing me for the last few weeks is the nature of the driver pins (upper-center) and the design of the exterior of the plug.
To both sides of each pin chamber in the plug is a shallow groove which deepens as it moves away from the pin; the driver pins are actually two pieces, a T-pin style pin combined with a shallow master wafer/pin which sits between the narrow stem of the T-pin and the key-pin.
When attempting to pick this lock only one or two of the driver pins will actually be holding the plug in place, the others will usually be held with their stems at the shear line. These 'gatekeeper' pins are always the first to bind and when raised so that the stems are at the shear line, the plug will fall into a deep false set. If you are particularly unlucky, all of the T-pins will be raised high enough that their stems will ride into the grooves in the plug which will trap the plug at ~90 degrees rotation.

Has anyone seen this design before? Is this design just for pick-resistance or is it part of some sort of special 'semi-master' functionality?
And finally, does anyone have any ideas how to pick this thing?

[nite0wl]

Some help IDing the keyway might also narrow things down.

There is a lookup code hand stamped on the reverse of the bow (not shown), putting this code into Codes On Line returned a keyway/blank number of Corbin/Russwin 60-5/CO87 or Ilco 1001EH, this is not quite right though those blanks would probably fit this keyway.
The bow is shaped similarly to a Russwin type blank except that the bow comes to a shallow point over the ring hole instead of becoming flat.

[nite0wl]

Looking through a Corbin-Russwin catalogue, I was reminded of "Hotel function" cylinders, in which a pass key (or change key) turns the plug 90 degrees in order to disengage the latch but not the deadbolt, while a higher level master key ("Emergency Master Key" in Corbin/Russwin parlance) can rotate the plug 360 degrees to disengage all latches and bolts in the mortice set. This particular lock does not seem to use currently available Corbin/Russwin drivers but the tailpiece cam and some other features seem to be similar to parts Corbin/Russwin lists as for "Obsolete deadlocks: Corbin® 610 Series and Russwin® 1403 Series".

[Raymond]

Obviously the key must lift all bottom pins and wafer just to the point that the plug turns below the wafer. Any turning pressure will leave the wafer trapped above the shear. Therefore the best way to pick is by overlifting to try to keep the wafer above the shear. It looks deviously difficult.

Impressioning or code cutting a key might be easier because once you get it to turn and trap, just cut another key 25 thousandths higher.

[nite0wl]

I was afraid that variety of over lifting would be involved, it is one technique that has continued to elude me.

Examining the mechanism, and with the input of a few off-board people I had discussions with, the wafers are definitely required for the proper functioning of the key I have for this cylinder but the T-pin and grove design has been suggested as a variation on a hotel-function or Brinks-function cylinder which suggests that there should be at least one other key (the change key and/or pass key) which would simply raise the T-pins into the lips of the grooves to operate the latch.