I also received an improved replacement knob from support, but I tried installing it and found it horrendous. The grommit makes it next to impossible to get the knob onto the shaft properly.

I found that the replacement knob was enough, and that the grommet was not necessary. Those of you getting replacement knobs should try that first (but save the grommet in case you end up needing it later).

I needed the grommet for Brian Mihulka's translucent knobs, but did not need it for the official empeg replacement knob.