Ok I think I fixed it. I took both upper and lower mixers off. I took the lower one (the one that has the butterfly valve in it) and took the side cover off. I was expecting to have a bad gear or it was binding up, but it the gears were good. I cleaned the contact pad on the inside. I put it all back together and it works fine now. Thank God it works, that lower mixer from my local Linde dealer was $3,600USD