I've ordered two CIEM's from JHA. I'm careful to use a bite block to hold my mouth wide open while the cast is firming up. Some audiologists don't quite understand how important a tight seal is for these CIEMs. One actually suggested I move my jaw around so the molded piece would feel more comfortable. I didn't take her advice and the CIEMs were very tight to the point of discomfort, but my ears adjusted over a few days and the fit has been good. The second CIEM's were an easy fit from the start. Maybe because my ear canal was already stretched out ?
Hope you can get them fixed up for a better fit . . . !
I did use a bite block for the impressions for my NT-6 and so I'm not sure what went wrong (I actually sent Hidition an open jaw and closed jaw set). The strange thing is the fit feels tight in my ears, but I'm still having the isolation and blockage issues. Thanks for the encouragement, but I have a bad feeling I may have learned an expensive lesson. I just think it's odd that I used the Etymotic ER6 for many years and never had any problems.
I cannot remember where, but Hidition does have written instructions for taking impressions. In their instructions, they ask you not to use a bite block and to have a relaxed jaw as you would have while listening to the CIEMs. Their manufacturing process is probably tuned to this type of an impression which may explain the issues. I believe that they also use this type of guidance due to their unusually deep channels. The open mouth impressions are really only for a singer that typically has their mouth open while wearing the CIEMs.