For some time  I lived with a an erratic scroll wheel on a Pi4.
The pointing worked perfectly, scrolling down worked fine, but
scrolling up was erratic, sometimes not reacting and occasionally
"bouncing" backwards. At first I suspected mechanical trouble in
the scroll wheel but could find nothing demonstrably wrong.

Finally, on a whim, I unplugged the mouse from the keyboard hub
and plugged it directly into the remaining USB 2.0 port on the Pi.
That completely solved the problem.

Anybody got a hint what might be going on? I can understand a
USB hub not working right, but it's much harder to understand
how it could work right for pointing and wrong for scrolling.

The mouse and keyboard are both elderly Dell take-offs from
scrapped computers. The keyboard is model sk-8125, the mouse
is model mo56uo.

Thanks for reading, and insights appreciated.

bob prohaska

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