There's a roll pin that holds the power director lever to the shaft (under the platform) - make sure it's not worn. Ours actually broke and I had to use a nail in it to get home.
(If you remove the roll pin the hydraulic valve for the power director under the platfrom will move to neutral all on it's own - it seems to be spring or pressure loaded that way.)
Also, check the pivot point for the cross shaft under the platform where it connects to the tranny. Sometimes this wears and causes problems.