The circular clip indeed fits in those rectangular slots, just for diaphragm and retainer. Cover is separate.
The purge cover is a bonded combo of soft and semi-rigid plastic/synthetic rubber. You squeeze the bottom and grab the bottom back of the cover with a fingernail and pull it forward and up. It's hooked to the top of the case front, just above the diaphragm. Very nice fit, even after multiple disassemblies.
The purge cover is a bonded combo of soft and semi-rigid plastic/synthetic rubber. You squeeze the bottom and grab the bottom back of the cover with a fingernail and pull it forward and up. It's hooked to the top of the case front, just above the diaphragm. Very nice fit, even after multiple disassemblies.