I'm working from memory here from when I had my XT apart. I used automotive 14 vdc bulbs and they are still working fine.
If you think the heat/smell is coming from the circuit board, remove it and check the backside for scorch marks and possible loose solder joints or copper trace-strip breaks. If some simple component on the board appears to be burnt try to get a replacement at Radio Shack. Re-solder everything in any case.
I'm assuming you've checked the output with a voltmeter. If I remember correctly the board has 120 AC input and 12-14 dc output to the bulbs. Which would indeed make the circuit board heat up in normal operation. Notice there is a cooling air path by the very nature of the brushroll motor enclosure.
Unless I'm very wrong and it gets its 12-14 vdc from a fan motor winding...but I doubt it.
Is the smell electrical aka ozone or more like burning pet hair? Always the possibility that the smell is coming from musty dust bunnies created inside the fan motor housing - a common occurrence in motors that have the bulb socket integral with the fan housing. You know what I mean - these are often found packed with rug dust and if so it's likely the main motor vents inside are clogged, too.
But first, be sure the bulbs you're using are an exact size match from the Auto Bulbs section.
I'll check out my XT and other Furys tomorrow - Sunday - and let you know what I find. If the Furys use the same circuit board then a donor junker Fantom shouldn't be too hard to come by.
Dave.
