When light kit is 'dangling' from fan, the fan works - light works (separate dimmer switch for light & fan)... when I connect light housing up to fan body, light works - fan doesn't. OK with the theory that something is 'disconnecting'... how do I find out what?

Light kit usually 2 wires to 2 wires. The white wire is important that it is secured, it is common to both. Red and black is light and fan, won't say which, think you know. Sounds like white wire is your problem. Installing housing makes no electrical connection, verify all connections in housing tight.

Sounds like something is loose, if it works depending on whether it's hanging.. . Check all connections inside the switch housing. Confirm it is wired correctly. What type of control are you using and how is that wired?

General ceiling fan troubleshooting and help FAQ- Ceiling Fans N More (http://www.ceiling-fans-n-more.com/ceiling-fan-general-troubleshooting-and-FAQ.php)