Most motor shops can deal with relatively modern motors but not
antiques.  The old starter switches were very well made, unlike the
plastic types today.  Motor shops can generally replace parts but do
not machine or repair old ones.  I have never met an old starter switch
that I could not fix with a lathe, a mill, and a little cleverness.
There are many types of switches, and the fix will be different for
every one of them.  If you can't do the work yourself, find a
machinist, not a motor shop.

Best regards,
Spencer Chase