I have a Kerry Super drill which I bought and renovated about 20 years ago. It was in a pretty neglected state, but cleaned up well and I would never part with it. There is a photo in my album, but unfortunately it doesn’t show the side with the return spring housing. When I got the machine the original return spring cover was missing, but fortunately the clock-type spring was still there. I turned up a new cover out of ally, and it’s been fine ever since. The inner of the spring fits into the slotted end of the quill operating spindle, and the outer end fits into a slot in the cover. The cover is a shallow “cup” which the spring sits in, rather like the barrel of a clock. To tension the spring the cover is rotated in its housing in the drill casting, then locked with a grub screw. No drama taking it apart. Just release the grub screw while holding the cover and release the tension. The cover can then be pulled off complete with the internal spring.
Mike