get someone to operate gears and have a look for play/wear at the top of the g/box where the gearshift cables attach,in older transits there was a pinch bolt which came loose and caused problems,sorry don`t know if the newer transits are modified,the cables may need adjusting also,if you cant see any problems then the play wear may be in the selector housing where the cables attach,this can be removed,think there are about six 10mm bolts holding the housing on.
cdc
August 2011