So, your neon sign doesn’t appear to be broken, but has started flickering or just won’t come on at all. Don’t panic… try these steps first.

If the sign illuminates but a tube FLICKERs:

Pull the “on/off” pull-chain (on the power supply) …pull quickly on and off two or three times ending with it off …then wait for 1 minute. Turn it on again and the problem should go away within a few minutes (if this fix is going to work at all). Repeat this ON/OFF procedure a couple of times if needed. If it is a new sign and it still flickers after trying this “fix”, then leave the sign ON for approximately one week (24 hours a day). Sometimes it takes time for the internal gases to settle.  Also, it may require up to 48 hours to achieve full brightness from the first time a new sign turned on.

If the sign turns on for only a few seconds then turns off:

The neon glass probably has a small hairline crack somewhere which has lets the neon gas out. The sign will need to be repaired by a neon tube bender.

If the sign has DIM letters within a few days of getting the new sign:

The sign needs a little bit more time to light up. Turn the sign on for 24 hours/day and keep it lit at least a week. This should fix the problem.

If the sign will not come on at all, not even for a split second:

Try to plug it into at a different wall outlet that you know is working. If it still doesn’t light up at all, it may be the power adaptor/transformer.
The adaptor/transformer from most manufacturers is warrantied for 1 year, so contact them for a replacement or to purchase a new transformer is it is out of warranty.

If a one year old sign has DIM areas:

Take the sign down, plug it in and turn it on. Hold the sign up over your head facing you. Be very carful not to touch the neon glass as it breaks very easily. Locate the very tiny mercury balls inside of the glass tubing. After you see them, tilt your sign so the tiny balls move to the area of the tubing that is not lighting up. After redistributing the mercury balls, leave the sign on for 20 minutes. If this was the issue, then it will regain its full brightness in the dim areas. If it is older than a few years, it may also need to be re-pumped with neon gas.