I have been using my CPAP machine for about 2 years now and have found it of benefit. Lately however I have noticed what appears to be excessive air leakage from the mask through 2 small holes about 3mm wide at the bottom of the mask. I don't know whether these holes had small plugs put into them that have since fallen out but the air leaking seems quite substantial and very noisy and off putting when trying to sleep. Shoultd I just block them off or should they be kept open. Hope someone can help.