Recently purchased a Oliver 550 with an aftermarket front end loader. In the process of cleaning the years of grease build up to see where there may be possible leaks in the lines/fittings etc. Fluid barely registered on the dip stick. I've added fluid so as to work the loader. Bucket works fine up and down. The main loader cylinders are very slow to raise. Tractor is equipped with the double feed back system and I have yet to change the hydraulic filter and knowing the previous owner it probably never was changed. Would I be correct in assuming that this may be the culprit and the system is oil starved? Is this maybe just the first step in trouble shooting the problem? The only site I've been able to find the filter was OliverParts.com. Any other sources for this as well as the breather element?