I have one of these machines, purchased it last fall and love it. Call sewingmachinesplus.com the have technicians who will help you to change the bulbs or find the problem. I purchased my machine at a local quilting store and they have not been very helpful when I've had issues, which are minor - like adding a ruler foot or glide foot - HQ makes them and also makes a conversion kit which I purchased for my machine from sewingmachinesplus - they guided me thru installing and now I can use any of the HQ feet on my machine. Handi Quilter (HQ) actually makes this machine for Husqvarna so the HQ parts work. When I asked my local shop where I purchased it about changing feet they told me I couldn't - I called Husqvaran and they also said I couldn't. SewingMachinesPlus said I could and they assisted - there are youTube videos as well as how install the conversion kit so you can use the other feet. I have only had it a short while so no issues with the light but they may be able to help again their customer services and technicians have been awesome. Good luck.
The foot that comes on the machine is like a ruler foot but not as tall so really doesn't work well with rulers - the HQ Sure Foot is a ruler foot and it works great now that I have put the conversion kit on my machine. This conversion kit allows me to use any of the HQ feet - just ordered a glide foot but haven't received it yet.
Here is a link to a page that tells you how to change the light ring
https://rhondabracey.com/2012/11/19/...sweet-sixteen/