What does a uncentered speaker sound like if you refoam and don't get the cone centered.

Try pressing with thumb and middle finger using both hands,basically four corners of a square on the cone ..equal pressure on the four points ...down with light pressure moving cone in and allow it to move back...do that a few times and if you feel rubbing its messed....the rubbing will sound like distortion  when audio is run through it....if you redo it again use shims so coil is centered.

Dont listen to MC ,he is wrong again...many recone kits come with  a new dust cap and will tell you in the instructions to remove old one with razor and insert shims etc...do what old hwymec is telling you. I use a single edge razor blade to remove cap cutting just above glue line as if you try to cut in the glue line the naterial is obviously too hard