Hi Everyone.
I just wanted to close out this conversation by reporting that
the advice given by Chris Baker and others was what solved the problem
of not being able to install mayavi because of inconsistencies between
various packages and versions.
The solution, which others may find valuable to know, was to
do a clean install of miniconda on a Windows 10 machine, and then
build everything using conda-forge by first typing
conda config --add channels conda-forge
followed by
conda config --set channel_priority strict
followed by
conda install python mayavi
-----------
I am now happily running Mayavi 4.7.2 and Python 3.8.10
and am receiving no errors.
This simple solution may help others with similar problems.
Many thanks!
Darren Williams