Before sending this in to the service center, you may want to try one quick fix. Remount your sensor on a new piece of foam tape. Whether you remount it in the same place or not, just make sure that you use new foam tape. The sensor is so delicate that it can detect even the slight amount of wear in the foam tape itself. If you are using the GY401, and you have it mounted on just one piece of foam tape, try using a second piece of foam tape when you remount it, this should eliminate the drift that may occur. Just remember that you will not need to use as much gain if you use the second piece of tape.