Mowing 3039r mower deck

[balzerja]

The mower deck on my 2017 3039r will not say in up position. Wants to drift back down to cutting position as it sits for a few hours. Any ideas

 

[balzerja]

Forgot to add this. My 3520 would stay up. After I got done cutting, I would raise deck and it would stay there. Dealer told me this has a one way cylinder. Have to hop off tractor and slide out the cutting depth rod and pin it.