My FIL has a NH t4020 with a 810tl with 1000 hours on it. Just recently the curl started leaking down while running and when off. it will completely leak down in just a minute or two, enough you can watch it and see it move. there is no issue with the boom. If you curl it back it will pull back up and then leak down. the curl doesn't seem to be weak when lifting, just leaks down. there are no visible hydraulic leaks. this loader has a valve on the cross bar up front that I believe all 4 lines run into and 8 lines run out to the cylinders, I'm not sure how this works or its purpose. any help would be appreciated.