Help with an older skyjack 3220 won't go down

I have an older skyjack lift and recently we replaced the control box with a new one. That cured a lot of problems with the lift but now if you go all the way up and Mac it out it will not lower you. Only way if someone is on the ground and opens the dump valve can you get down any help would be great thank you

Help with an older skyjack 3220 won't go down