I am sorry to have to tell you that I found a serious problem with the lawnmower you borrowed last week. The mulching blade apparently struck a rock or other obstruction and was bent out of shape. The mower was inoperable in that condition.
As you remember, I demonstrated the mower to you when you came to pick it up, and it performed properly at that time.
I took it to the local Agway Garden Center and they replaced the blade, straightened the rotor, and tuned up the engine. I will pay for the tune-up, but the cost of the repair was $89.95 and I would like to discuss who should pay for this.