smell of burning from sewing machine foot pedal?

I have a newhome model XL-11 circa 1981 serial no 813027315. The foot pedal is a Janome type 22052 low or high speed switch at side of pedal because of its age it has no electronic circuit board just copper terminals and a 3" long white battery type installed by 15mm diameter which the smell of burning seems to eminate from any ideas where I could source a replacement