1997 f450 Bucket Truck

Hello, Wondering if anyone could help, My problem is : I have a 1997 Ford f450 bucket truck with a TELSTA 28-d boom on it, the problem is the boom tries to raise but only about 1" then stops , the same when you tried to lower the boom, all other functions appears to be working fine, it also has a emergency 12 volt pump that operates all controls with the same result when you raise the boom.
Any suggestions ??
Thank you !!
Bryan

1997 f450 Bucket Truck