JD 2630 Hydraulic Issue

I just got a 2630 with a Deere 145 loader, dual remotes that have been converted to Pioneer quick connects and all seemed to be working fine when I looked at and drove the machine before making the purchase. "everything worked" as expected for a 45/46 year old tractor. Got the tractor home and did the normal oil/fluid and filter changes. Screen was dirty as expected ( no metal debris ). Tightened up oil pan bolts, cleaned radiator etc. Generally, did a real good cleaning and servicing. Everything still working fine. Used the loader to move some things. All was good. Hooked up 25A Flail used it for 10/15 minutes to make sure that PTO was working. All was good. Still checking for leaks and just doing overall inspection to make sure that I've got no "major" issues. The only visible issues is a hydraulic line leak on old hose on the loader. Time to put the tractor to work. Hooked up 10' pull type Bush Hog bush hog and went to work. WOW! Great tractor but after a several minutes (10/15) I noticed that the loader had drifted up. So I lowered it back down. After 10/15 minutes it had drifted back up and so had my hog. So, I thinking that maybe I had bumped the remote control lever and cause the hog to raise. So, I think I will move the hose to the other remote because the lever is shorter and closer to the seat and less likely for me to accidentally bump. When I go the back of the tractor to move the hose I have hydraulic fluid coming out of the filler cap under the seat. Back to the barn, removed and cleaned the filler cap and back to hogging. 30 minutes or so of hogging and I have fluid coming out of the filler cap. ???? Thanks for any advise. WJH