singer goes on without foot on pedal?

i have a very old singer, its green with a light, im not sure what make it is. i was in the middle of sewing when all of a Sudan it went mad, so i switched it off from the plug. i then cleaned all the cotton out of it, now every time i plug it in it goes mad without my foot on the pedal, i opened the pedal up to see if the connectors were touching but from what i can see everything is where it should be, thank you in advance for any help given.