Fuel control roughly 60 rich. Push throttle above crossover tit corrects roughly 820. Pull throttles just below crossover tit stays at 820. Below crossover tit will only correct back when switch is placed to NULL. All TD ops checks work as advertised. Valve is going to a locked position below crossover with the switch in AUTO. Considering the valve works like a champ in AUTO and also in locked not suspecting the valve to be the culprit. Changed AMP, coordinator, & relay box. Have never come across this issue before any ideas?