The toilet is leaking from the base when it is flushed the water goes down but has very little water left in the bowl

Call a plumber.

If it is leaking from the base, you have a bad wax seal. I will assume you found this while plumbing. Draining like you indicate is usually from a clogged toilet rap or main drain. Toilet must be removed for the ring replacement so then is a good time to check for a blockage in the toilet trap or main line. You may have to have someone auger the main line.

Call a plumber.

How is this a helpful answer?

If it is leaking from the base, you have a bad wax seal. I will assume you found this while plumbing. Draining like you indicate is usually from a clogged toilet rap or main drain. Toilet must be removed for the ring replacement so then is a good time to check for a blockage in the toilet trap or main line. You may have to have someone auger the main line.

Could the toilet itself need replce

Since the toilet is only leaking when you flush, odds are a back wax seal as ma suggested. If it were a crack in the toilet, it would most likely leak even when sitting idol. However, when you pull the toilet to change the wax ring, you can set the toilet up on some saw horses, fill the tank and give it a flush (outside of course) and make sure water only comes out where it should.

Now, all that being said, if you are looking for an excuse to get a new toilet, now would be the time. Standard toilets are not all that expensive (right around 100 bucks). ADA (taller toilets), colored, or fancy models can run the price up quickly.

How is this a helpful answer??

I too had this same issue and eventually had to get the toilet replaced. I had to call a plumber for this.