Although I have not tried this on a Wurlitzer ratchet wheel action
(wish I had one!), this is what was done and still is done by those of
us that have leather belt driven lathes.

There is a substance called 'belt dressing', a mixture of rosin and
beeswax as I recall.  It comes in a stick form and is applied by
holding the stick against the moving belt to get an even application.
I have a small quantity and could cut off a chunk for you if you like.

Again, I have not tried this.  It could be the totally wrong way to
approach this problem.

Bill McGown
Mississippi
"For every complex problem, there is an answer that is clear, simple,
and wrong."  -- H. L. Mencken