i have a 6 stop miprom 21 that runs fine in both directions but in the down as it starts down it drops ntsi input but still runs fine except as it comes into bottom terinal it starts to slow down then seems to speed up then slows down correctly. It all happens within a second or two. The only faults i get is one that indicates ntsi has dropped. this problem surfaced about 6 months ago and i checked relays and the speed board and it went away for a while. Its 350 fpm. Any input would be appreciated.