I have a five years old Pioneer VSX-808RDS receiver. The volume
control on the receiver is not working anymore. If I turn the knob to
lower the volume, the volume increases. The overall response to the
knob turning is erratic. A friend told me the pulse gauge/detector
(whatever the name is in English) for the volume knob had
malfunctioned and that it is pretty common.

I'm wondering if someone here has had the same problem and if it is
possible to buy a new pulse gauge to replace the broken one.

And how do I remove the volume knob from the receiver? I've tried
before, but couldn't work it out.