I have a Otis pie selector unit that won't stop in the down direction if you place a call from a top floor it goes to main floor then up to the selected floor I'm a helper not the lead mechanic but we're not having much luck so I figured I'd ask here thanks.

Does the selector have an advancer, or is it just a normal pie plate selector? The floor bars make a contact on the moving selector. Also look at the travel cable for the floor stopping switch. there is one for hall calls up and down, and one for car call stopping. you should find them easily on the wiring diagram. Assuming you have one. The advancer was on gearless machines that ran like 500 fpm. A 350 fpm geared machine was just a normal pie plate config.

Thanks for the advice we got it figured though, broken wire on the terminal for the DCS. I Hadn't worked on this type of unit and it's past due for a mod but was a good learning experience.