@Gary678* - thanks for the input. And great idea to verify supplier's source.
@alexisaki - after research on reputable rebuilders and finding many not in the business anymore; then settling on a gentleman who got great references from people I trust; sending the horn to him; and him not being able to continue the work due to illness; after waiting 4 months - I'm going with the new horn for the timing, as well as the reliability and, yes, a period of warranty... Oh, and the fact I, personally, don't have the talent, nor the patience, to do the conversion/rebuild myself
