My older model mf 235 lift is not working correctly. It is either all the way down or up. it only comes up when it wants to. I have been running a 5 ft rotary mower behind in the controls in the up position and it just comes up once in awhile. I have draft control and lift speed on this tractor. I do not know if this is a control issue or hyd pump problem. I have changed fluid and filter. I am a pretty good wrench but do not know much about the hyd system. Need some of you MF gear heads out there to help me get started to figure out my problem. thanks Robaton