I know this is an old topic, but I wanted to add some pictures of the latest sr-007 so that people can see if there are any differences. I did the blue-tac mod on the port and increased the spring to 105mm and flattened it as recommended. I inserted the spring as per the old -007 model as shown in the instructions (credit to spritzer for the instructions sheet picture). The difference in bass was actually quite moderate. It did help with bass response, but the change was subtle. Which is really all I wanted. No issues with the Stax fart at all so far. See attached. This was purchased Dec 15 2017 directly from Stax in Japan.