7.6.1: How do I "roll back" video driver to earlier Knoppix?

["Andrew" <knoppix@rngresearch.com>]

Dear Klaus et al,

My video is broken with 7.6.1, but used to work fine with earlier Knoppix
versions.  How can I "roll back" the driver(s)?

I tried upgrading to 7.4.2 when it came out, but couldn't get the video to
work on this machine (it had been working fine Knoppix 6 versions).  I
figured I'd just have to wait for the next version.  I tried Knoppix 7.6.1
and it has the same problems:

1. Without cheatcodes, video comes up 800x600 x 8 bits.
2. I tried boot: fb labels and the gui is almost usable, except that video
is extremely sluggish.
3. I tried screen, depth, and video cheatcodes, and, instead of a speed
problem, many screen updates are getting lost (objects leaving a trail of
'debris' when moved across the screen and not appearing where they
actually 'are', etc.)

What do I need to do to get 7.6.1 to handle my video like Knoppix (3, 4,
5, and) 6 did?

Best regards,
Andrew