Ott Lite quit working, replaced bulb, examined

You should probably replace the bulb. If the filament is broken, the heat will cause it to open and close as it heats, expands, then breaks contact and cools again. This could also be a problem in an internal connection that is intermittent. Heat causes expansion of parts and that expansion breaks the connection and the flow of electrical current. When it cools off, it makes contact again and the process repeats itself. As the point of break in the current wears from repeated heating and cooling, the contact widens and the time takes longer.

This problem will likely be at a connector, the switch, the bulb socket, or in the bulb itself.

If a new bulb does not work, then it is most likely something else, perhaps the wiring or a connection. You can probably have your machine serviced to get it fixed, or go purchase a light that you can place close to your machine to light the sewing area. There are lights available with attachment clips and a bendable neck that well let you get the light in the right spot. There are also strings of LED lights available on eBay that you can attach to the upper part of the throat to light the work area. I replaced my regular sewing machine bulb with an LED bulb and was surprised how much better it lights.

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Normally the light bulb function should not affect the machine's ability to operate, however, it could be if your machine is a computerized model. Try replacing the bulb and then test.
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look on the left side of the machine and see if you see a little round plastic circle, very very carefully use a screw driver to pry it out , there should be a screw to unscrew and the side should come off so you can replace the bulb. if you will send me a comment with the complete name and model number, I'll see if I can find you a manual.

Replace the screw. This model has a twist & click bulb. Push in, twist, and pull out. Be careful. If the bulb is quite old, it can be brittle and break.

I'm not specifically familiar with the 830 model, but all the other Berninas I've dealt with are very similar.

First, disconnect the power cord from the wall socket - safety first!

The housing for the lamp is in the hinged piece at the left (needle) end. It's hinged at the back (two hinges, one above the other like a door) and it's simply a matter of placing the palm of the left hand over the lamp switch with the thumb on the front above the needle and the tips of the fingers at the back of the machine, then opening the housing by twisting it away from the body of the machine from the front. It's held closed with a spring clip, so a little pressure may be required.

Once opened, the lamp and its holder are easily accessible. Remember the lamp is probably a bayonet fitting, so a little pressure to push the bulb into the contact springs and a slight twist in the same direction as you would turn a screw to undo it, and the lamp should come out. Avoid too much pressure on the lamp, as the glass part can part company with the metal base. If it does break, getting the metal base out is a bit of an issue, but it can usually be achieved with a pair of long-nosed pliers. Be very careful not to break the lamp holder - they can become quite brittle.

Having obtained a suitable replacement lamp of the same fitting size and wattage (most are 15 W), fitting it is simply a matter of pushing the lamp base into the holder and twisting it to lock it in place, then closing the housing.

yes, the light need to be checked, for your safety,& to see what your sewing, good lighting is very inportant

I have had this happen and found the switch was broken and not making contact inside the machine. We prepped the plastic and use a two-part glue for plastic.

I don't know how long the repair lasted as I sold the machine.

Did more research and found the answer on a FREE site.

I had the same problem and was sewing for quite awhile without my light working. Finally, a friend of mine was over and we did get it replaced. I believe there are a couple of plastic tabs behind the machine, and we pried them off and there was a screw behind them, (I can't remember if there was one or two plastic tabs) when we unscrewed them that popped off the cover and I was able to replace the bulb. I hope that helps, and when I go home I will check it again to see if I missed anything. Good Luck!!