I just bought a 2840 . The lift & loader puts a strain on motor when you operate eather one. After a while in operation you get a jerking movement as you operate.Is the valve sticking or pump bad?
You should get that thing into a good dealer to do pressure and flow testing. Chances are there is a high pressure leak some where in that system. It's a closed center system which doesn't pump oil until it senses a pressure drop. 30-40-50 series were notorious for these. It wasn't until the 55 sereis they finally got everything or close to ironed out.