IML: steady drop in EL brightness?

Just now starting to drive and enjoy my 63 custom but noticing a dimming of the panel lights as I drove across town saturday night to a car show. The dimmer does work; the overall brightness range is just depressed. There is also the annoying pulsation of the regulated voltage on the entire grid; my DVM at the battery rhythmically oscillates between 14.2 and 15.7. I speculate these are unrelated separate problems but maybe not. Another theory I have sees the power pack heating up over time and dropping output voltage. Has anyone noticed this symptom? My next test will be to put the DVM on the EL output and monitor it over a long haul.

I must say I am shocked how few people notice the car as I go about Tucson Arizona. No looks, no whistles, no horns, nothing. It's not like there are hundreds of them out there. I expected more than this though. Maybe the desert heat toasts our brains and we have become oblivious. --Tom