Yesterday, I used my new SpeeCo 5-Ton electric log splitter for the third time (first couple of times were about two weeks ago in warm weather). It was cold here in CT, but not freezing. The ram started at normal speed and power, but about 3/5 of the way into the split, it slowed down to a crawl and then stopped before hitting its full extension. It also did this without a log in place. The ram returned at normal speed. As required, I had loosened the vent plug for the hydraulics before each splitting session. Any thoughts on what is happening?