My Aga stove quit, pilot wouldn’t stay lit. I replaced the SIT 630 regulator, as well as the thermocouple, cleaned it up and re installed. Pilot comes on, main flame came on, then died. Pilot still on, no main flame. Turning the knob has no effect. I transferred the minimum requirement screw and fixtures from the old 630, pressure is factory set. Diastat bulb not crushed, diastat tube in it proper channel. Ideas? Gas pressure to valve is fine.