3000 3pt doesnt lift when cold

[Patf10]

So I have been having some issues witht he 3pt lift on my 3000. When it is cold, the lift doesn't lift. I have to let the tractor run for a long time before it slowly starts to lift. Once the entire system warms up the lift works fine and can lift all the weight I want to. My filters are fine, I changed them a year or so ago hoping to solve this same problem. Im thinking I have some sort of stuck valve or something internal that when cold cant move correctly. I don't think it is a pump issue as when it is warm out I never have a problem.

I have read about a valve internally that tends to stick but I cant remember the name of it. Im planning on pulling to top cover and cleaning, going through the whole system. What parts should I pay particular attention to, and what should I buy in advance to make sure I have the parts?

Thanks
Pat