Not sure about the part but my machine was whistling and I put a small bottle of water on it and it is quiet now, I also got tired of the face farts caused by the face gasket andtie4d a handkerchief around the mask so the handkerchief would cover the entire gasket area - no more face farts and I have been using thew same gasket for 4 YEARS and it is still in good shape. The strap system is the one that frustrates me and I am going to "line" the strap on the inside with fabric and \\\then zig-zag stitch it so it can't fall apart and still has the grip side so the velcro can grip it. The fabric should strengthen it enough so the strap won't fall apart. The hard part of the mask lasted at least 4 years and mine is the old full-face model and the adjustment part finally broke. I may have been able to fix it with the new ultraviolet glue but I didn't have the glue when it broke. All those parts are frustrating when they break and Amazon is the only place I have been able to find them