My Harman P61 was built in 1998, stove has been great but last year I tried swapping in a new circuit board because I wanted the draft blower adjustment and I had read the updated algorithm may be more efficient. I originally tried running the black ESP and had the dipswitch on the board set accordingly. I dialed in the draft blower to spec with my manomteter but the stove wasn't burning for crap, and kept pushing pellets even with the feed rate turned all the way down. I thought maybe I had a bad ESP so I ordered a new black one, same thing. Ordered a red one, changed the dip switch on the board accordingly, same thing. Put the original board back in and she was running like a champ. Pictured is the original board I just put new potentiometers on. I would like to get this figured out so I have a backup board if needed, 25 years on a circuit board is a pretty good run and while i have high hopes for my original I always like to have a good backup plan.