Slow Loader - Spool Valve Problem

I received the following the other day: I purchased a two-spool control valve RD522GCGASA4B1 on 4/27/11 from xxxxxxxxx.  The unit is mounted on a '65 Ford 3400 with front end loader.  For the last 3 or 4 months the lift cylinders have been going up real slow at 1200 rpm.  If I increase the rpm's to 1800 it goes up a bit faster, but not much.  The lift cylinders are connected to the spool valve next to the relief valve.  The bucket cylinders snap bank and forth real fast with or without a load.  The normal load on the unit is a 900-1000 lb round hay ball.  

The other thing I noticed is that the spool valve for the lift cylinders will go to the bottom and hit a hard spot, then when forced with the handle will continue down and unload the lift cylinders allowing it to fall fast.  Is this normal?

I contacted your distributor they referred me to xxxxxxxx at your plant.

My questions are:  1 - What would cause this problem?   2 - If it is the spool valve can I fix it with new parts?  

These are typically easy issues to get thru depending on how much folks know about their system, sometimes they can get tricky.  The following are my comments:

The RD522GCGA5A4B1 doesn't change the flow rate or generate pressure (it does have a pressure relief cartridge at the inlet).  This valve takes the inlet flow and directs it to either the outlet, or one of the 4 work ports.  In the float position the inlet and work ports are connected to tank.  (http://www.princehyd.com/Products/Hydraulic-Valves/Mono-Block/25-Gallon-Three-Spool will provide details on this valve is a flow directing control valve.)

Cylinder speed or movement speed is determined by the amount of flow that is available.  With a gear style pump, increasing the pump speed or RPM’s will increase the flow rate or cause the cylinders to move faster.  The cylinder bore is another item that can affect cylinder speed.  A large bore cylinder (lets say 6 inch bore) being filled with 10 gpm’s will extend slower than a small bore cylinder (2 inch bore).  This has to do with area.  The 6 inch bore cylinder has more area to fill and is going to fill up slower than the smaller 2 inch bore cylinder.

You mention that shifting the handle in a certain position will cause the loader to fall fast.  This is likely the float option and based on your description, it is working fine.

Here is some information on trouble shooting a hydraulic system.  

Loader Valve Trouble Shooting maybe helpful also. 

Parts Manual for the RD5200 Valve.

With a pressure gauge these types of problems are usually easy to resolve.