The left Q1 liquid He level dropped to 45% for several hours this morning. The supply valve was open, and the magnet did not respond for almost two hours. I went into the hall and confirmed proper operation of the JT valves, and saw no evidence of relief valve activity. We are seeing an increase in pressure in the magnet at irregular intervals. This is causing the intermittent drop in liquid level. We have not yet discovered the cause of the pressure fluctuations. I have asked to be notified of any opportunistic openings, I would like to check the vacuums on the magnets He return lines. The trip point for this magnet is 20% liquid level, so we have a little room with these oscillations.