Allen wrench 2.5 mm
This size of hex key you need for changing the football players. This key is free with a new football table.
Also with a set of playing figures (11 players plus 2 dampers) this key is included.
In case you want to replace the bumpers, you need to remove the football players in order to slide the bumpers over the rods. If you lost the hex key, you can order a new one together with the bumpers.