Domestic homes designed as a brick peir, bearers and joists building have a loading of capacity generally around 100kg per square metre - so given that a pinball is around the 125kg and not implying but the average is around guy in his 40's is probably 85 kg = 230kgs over 2 sqm.  Pinball weight is point loading to the floor which is worse than say a pallet weighing the same amount. All depends how old your house is, size of your beams and if it is hardwood or treated pine.

The problem is that the weight of the pinball is distributed over the four legs = 60kg for the pinball at the front plus the guy playing meaning 145kg plus any spectators = wobble and overloading especially if there are no joist in the section of the floor.

My advice would be install 2 steel I beams directly under the joists supporting where the front and rear of of the pinball legs sit. This may not be possible or more difficult if your bearers and joists are going 90 degrees to what you want to install. These I beams are then supported by a 400x400x400mm concrete pad footing and then a small brick pier.

Hope that helps.