I'm new here. I purchased a 753 with 3900 hours on it. Runs good, but, in cold weather, I loose hydraulic power in both bucket and movement functions. When I try to eitrher move or lift, I heard a rather loud "groan", feels like things are vibrating, as if it tried and couldn't do what I wanted. If I am moving fairly slow, going along fine, and try to increase speed, or turn sharp, I'll get the same groan and power dies. Any ideas? The machine was purchased at a Bobcat dealer, and all filters were changed at the time of sale. Could the hydraulic old be old and thick? Is there a relief valve that could be opening too fast? Thanks in advance.