spindle speed

Which version are you using?

For 2.9 you can download and install one of the most recent debian packages from the buildbot like this: buildbot.linuxcnc.org/dists/buster/maste...gb2e28a88c_amd64.deb

But for 2.8 a haven't found a recent deb package. I thought there is a recent one as well....
Maybe you have to build your package yourself or you have to wait for the 2.8.4 release.

I have an alternative. You can install my custom version, it has some more fixes than the official 2.8 version:
buildbot.linuxcnc.org/dists/buster/scrat...~f8cf6eff7_amd64.deb