The woofers dust caps were foam and deteriorating as well so were replaced.
Millersound designed a new replacement dome system that is based on the dust cap of the 12in woofer. They are the only ones that replace domes on original Polydome K midranges. They have gotten good reviews for their work, so decided to give them a try. Everything seems very well done.
All the rest of the replacement companies have designed new Polydome style drivers. There are at least 3 of them that make new midrange units. Problem I see is that the Kappa 8 speakers rated sensitivity is 89dBSPL/1w/1m. One of the replacements is 83dBSPL/1w/1m and another is 81dBSPL/1w/1m sensitivity, so do not seem to be a good fit for replacements. One designed by Vifa/Scan Speak is 92dBSPL/1w/1m, so it should be a good fit, but it is the most expensive replacement driver.
