Oceanic Delta 4 front cover removal

[JAYW]

My Oceanic Delta 4 purge crumbled like a few others noted on this forum. I have no issues finding a replacement. But, I cannot remove the cover that holds the purge. I've tried twisting to no avail. Anyone have experience removing the cover?

 

[tursiops]

My Oceanic Delta 4 purge crumbled like a few others noted on this forum. I have no issues finding a replacement. But, I cannot remove the cover that holds the purge. I've tried twisting to no avail. Anyone have experience removing the cover?

It should just unscrew. What helps is a grippy non-slip holder to hang on to it. Some silicone jar-lid removers work. What also can help is to soak the unit in warm water, and even to apply some 50-50 white vinegar-water mixture to the crack where the retaining ring hits the case.