Vickers Variable Displacement Piston Pump and similar items

Vickers Variable Displacement Piston Pump Model# PV2003-12-AB-S476 Assembly# V-235655 Rebuilt is written on the side of the pump. The shaft turns smoothly. Picked this up from a local factory it was covered in black grime including the caps. Everything on the shelf was covered in same grime. Not sure if this has been used since rebuild. It's grimy coating was from years on shelf not use. Because of time on shelf it should just be gone through regardless. I did a quick wipe down and that's how it looks now. There is a very small amount of in and out play of the shaft. When you rotate the unit you can hear the piston slide - not sure if it's just the nature of the unit or if something is wrong. I would just suggest going through the pump before use.