siren problem

A few days ago my siren quit working, well I thought it did. Something inside the siren is flaky. It basically works when it wants to. But today I went and listen to the siren close up and it still does work, but the sound is very very soft. In order to hear it, you need to have your ear right up to it, and even then its very hard to hear it. I had already taken it apart 3 days ago. Nothing looked wrong by looking at the board, but then after messing with it alittle, I finally got it to work. It worked from then until this morning. Does anyone know what could be wrong, and/or where I could look for on the board?

Have you used a volt meter to verify the siren is getting 12 volts?   If it is getting the proper voltage, you need to look for bad solder joints on the board.  If you can not see any bad joints, with the siren connected to a good 12volt source, tap on the board with the plastic end of a screwdriver to see if you can find the bad connection.

Have you checked your ground????

Ok to answer all your questions.... The siren was getting 12V because when I disconnected it, I ran its power and ground wires to the battery and I had the same problem. The siren output on the alarm is fine. I checked the entire chip board for any loose solder joints and found nothing. All the resistors and other "things" are in good connection. I did tap on the board and still had no luck. The ground was moved and still no luck. I have already ordered another siren. Is it possible that the siren got alittle messed up from the engine heat?