Just a note here.
I am in the process of reworking the controls on a Whitfield Prodigy II
I decided to use a programable and adjustable Mosfet relay setup to control the on and off time of the feed motor.
The relay allows me to adjust the on time span of the feed motor and tweek it right in where the factory board had
Also I can vary the off time (heat range of the stove) from 1 second to 10 seconds
(factory settings were the same)
The start up sequence is accomplished by the use of a one shot timer that will power the feed motor until the low side snap switch is engaged.
The rest of the stuff is basic wiring 101 Use a a standard HD dimmer control to vary the blower fan depending on whats needed.
The exhaust fan (depending on the stove) can either run full speed or be set up so you can control it.
The factory boards were built to try and keep the operation as simple as possible BUTTTTTTTTTTTTTTTTTTTTTTT
Unfortunately many of these older boards were not all that well made and as you already know, hard to find now and $$$$$$$$$ when you do find them.
As long as you keep all the original safeties in place with a door switch, pressure switch and the high and low snap switches you set and safe.
As I depend on my stoves for heat in the house and not just asthetics, I want easily replaceable parts that I can get "Off the shelf"
I contacted Precision timer company and spoke with Jim
I am using a model 646 solid state controler for the on and off cycles and a model 644 timer for the start up
These are all built to whatever spec you choose from the list of options.
Basic type
Voltage
On time specs
Off time specs
and several other options
These are about 2 inches square and an inch thick and have standard 1/4" spade connections
They come with a full schematic to wire them in with too
My bigg issue with most of the control boards is that they are made overseas and when the die you are SOL and have to replace the whole board.
Many of these boards can and do fail if the fan motor dies and or the feed motor goes south.
The components are in many cases extremely sensative to voltage ups and downs (power outages)
The Industrial cycle timers are designed to be very robust and caome in Amperage ratings of 5-10-15 amps or more.
Having the cycle timers only running the feed motor and not intertied with other components will lessen the problem of failure greatly.
Here is a link to Precision timer
http://www.precisiontimer.com/
Just a FWIW
Good luck with your rewire and keep us posted.
Snowy