Watch this helpful video to learn how to identify and fix weak-flushing toilets.
If the toilet won't completely flush, you may have a problem. Sometimes it won't completely flush because the flapper is not getting enough lift to drain the tank.
Be sure to check that the chain is attached to the flush lever and has enough give and pull. Check the chain for slack. If the tank is not getting enough water you may need to adjust the fill valve.
They video show easy steps to fix weak-flushing toilet problems.