I apologize for not taking more pictures but now that I have the device assembled and the oven control calibrated I don't want to disrupt the cell any more (It is stabilizing now). So I'll have to answer with what pictures I have taken to facilitate reassembly (as wires tended to break at the solder joints) accompanied bu a textual description. I hope it helps...
First 2 pictures (don't know why the images are rotated) - this is the cell "baking" - cell temp is about 37.2C. The brownish wire coming out of the thermal well is a PT1000 RTD.
Oven is a stainless steel cylinder about 5cm diameter and about 9-10cm long. It has a connection panel below it. In the picture you can see the outer jacket with the expanded polystyrene foam insulation. The insulation cover all of the oven - with cutouts for the wires, thermometer well, copper connections, and wires.
Under the bottom cover a Mullard OC28 serves as the heater. See diagram in previous post. It is connected to a steel panel that has a bakelite standard cell and PCB holder. It is barely visible under the board in the next picture.
In the picture the jacket is also visible in the background. If you look closely at the bottom bracket you'll see that thermistor well for the GT25 thermistor (the red wire going into the well is one of the thermistor wires). The thermistor measures the heater temp - not the cell temp.
The top of the cell is held by a bracket that also houses the two trimmer potentiometers (Red and Black). The cutout in the bracket is the shape of the cell with a small indent to hold a thermometer against the cell.
Not pictured:
I do not have a picture of the cell - but it is encapsulated in hard heatsink compound, wrapped in a stainless jacket and then with something like a PVC jacket over it. It is held snugly by the top and bottom brackets.
Outer thermistor - an indent is molded in the Styrofoam and the GT24 is snugly connected to the outer aluminum jacket by a bracket and 2 screws.
At the opposite side (and bottom - probably trying to get this heat source as far away as possible from the thermistor and cell) in a square indent in the styrofoam - is located the tiny box with the resistors and zener.
A very nice device. Sort of like a poor man's LTZ1000 or LM399 - albeit I am not sure these were cheap when purchased back in 1966....