Working on a L2650 for a friend. Tractor needs clutch in it. I pulled it in front of my shop and took loader off. Started tractor and now the 3pt won’t lift the tiller on the back. I called another friend and he told me I had to loop the hoses to make hyd system loop work. I did that but still nothing. It was working perfect before I took loader off. Wondering if I caused an air pocket or something. I also found the sight glass by clutch pedal. It is almost all the way full with fluid. I noticed there is a fill port on top of transmission. I assume the sight glass is for the transmission. There is also a fill port on top of rearend. Is this one common system or is it two? If so where do you check the level at the rear? Tractor has a shuttle shift transmission also. Thanks for any advice on this.