Apparently, the problem was that the nut and bolt that held one metal unit connected to another metal unit by a pulley (similar to your fan belt) had worked its way loose.
The repairman borrowed my tools and asked me to give him an exact size nut and bolt to replace the old ones. (Don't repairpersons carry their own tools, parts and supplies anymore?) Paid him $120, no charge for using my tools and nut and bolt.