SR175 Lift seems weak and soft

[mason1970]

Hello , 2011 SR 175 , 350 hours The lift feature does not have great power like it did . Have to rev it to get power or even lift the front wheels off the ground , then it wants to slowly drop back down instead of staying . All other functions seem normal . I tilted the cab and could find no leaks . Other things notable would be the hydraulics continue lift action for a second after controls are released , kinda spongy . Oil filter was changed at about 200 hours and double checked since , it's spotless inside , oil looks as clear as new . I'm guessing a check valve somewhere but no clue where to start looking . Hoping someone has some experience with this . Any help you can give is much appreciated .