hello, new to the forum here. so I purchased new th400 reverse manual valve body , transbrake , ptc converter. so my trans has park , reverse , neutral, when I select 1st I can feel engaging into first then when I let go the brake car moves about foot and locks up. second gear is there, not sure about 3rd. this happed second time. first time I drove the car around block in 2nd and my trans builder told me to pull it out . results, welded 5 direct clutches, bad direct steel plate, bad low band, bad 34 element sprag. builder claimed that I shifted trans backwards. not true. now I got the trans back in the car and same problem. please help. thanks