Take a pail of water and VERY slowly pour water into the bowl. It will fill up until the level gets to the point where it overflows the weir. If you can cause the water level to come up, and stay there, then you have a problem in the refill . If it does not come up, then this is what the toilet is designed for. If the toilet is not level, front to back, this can affect the water level. Check that out as well.