Slow and shuddering hydraulics

[hugho]

I think I have a MF40 commercial tractor which has been in Ag for decades. It has about 5000 hrs.It has the instant reverse transmission and a rather useless transmission driven PTO. and a three point which only works when you are moving. Otherwise It is in fine shape and the commercial HD front axle is a real plus because the previous owner put a larger custom bucket on the FEL which is useful for snow removal here in mountainous Wyoming. I have done a lot of maintenance on it including engine rebuild of the Perkins and converting the funky oil and fuel filters to spin ons. My problem is the hydraulics. I changed the oil and filter when I bought it hoping this would speed up the slow and shuddering hydraulics. Nope. I checked for kinks in the feed and return lines and saw nothing obvious. I don't know if there is another filter that might be clogged. Obviously I am working on the assumption that something is clogged somewhere restricting flow. I am full to the top with hydraulic oil and I wonder if there is an air leak somewhere but no oil leaks anywhere. I suppose the pump could be the problem but I would have to test the pressure somehow or put in a gauge. The pump is driven off the front crank by a shaft and seems quiet and smooth. Is there something I am missing?? I assume to test a pump you need to be able to test both pressure and flow.