The 601 series was built between 1958 and 1962.
Nice little tractor.
There is a great deal of information about Ford lift problems in the archives. Generally, one starts by removing the access cover on the side and looking inside with the engine running and something heavy on the lift (lift control lever in raised position) to see if oil is leaking from, for example, the end of the lift cylinder.
You will need a flashlight and, perhaps a mirror. You may need to drain down the hydraulic sump a bit before removing the cover to avoid loosing oil.