Why does the 3 point lift on my 2260 long tractor not working and how can I fix it?

I inherited my father's 2260 Long Tractor after he passed away. About 10 years ago the the 3 pt lift was operating but was a little slow once I started using it, it would work fine again.

Now 10 years later, it won't operate. I can physically lift it up and down by hand. I changed out the hydraulic/transmission fluid. I cleaned the filter screen. I took the lift handle off by the seat and inspected the key was still intact and in place.